Annual report pursuant to Section 13 and 15(d)

Securities Owned and Securities Sold, But Not Yet Purchased (Components of Securities Owned and Securities Sold, but not yet Purchased) (Details)

v2.4.1.9
Securities Owned and Securities Sold, But Not Yet Purchased (Components of Securities Owned and Securities Sold, but not yet Purchased) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned $ 5,910us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned $ 4,789us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
Securities Sold, But Not Yet Purchased (230)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased (83)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
Certificates of Deposit [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 465us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_CertificatesOfDepositMember 		24us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_CertificatesOfDepositMember
Securities Sold, But Not Yet Purchased 0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_CertificatesOfDepositMember 		0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_CertificatesOfDepositMember
Debt Securities [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 1,526us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_DebtSecuritiesMember 		1,402us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_DebtSecuritiesMember
Securities Sold, But Not Yet Purchased (45)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_DebtSecuritiesMember 		(46)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_DebtSecuritiesMember
U.S. Treasury Notes [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 102us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_USTreasuryNotesSecuritiesMember 		1us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_USTreasuryNotesSecuritiesMember
Securities Sold, But Not Yet Purchased (151)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_USTreasuryNotesSecuritiesMember 		0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_USTreasuryNotesSecuritiesMember
Common Stock and Warrants [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 1,981us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_CommonStockAndWarrantsMember 		689us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_CommonStockAndWarrantsMember
Securities Sold, But Not Yet Purchased (34)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_CommonStockAndWarrantsMember 		(33)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_CommonStockAndWarrantsMember
Restricted Common Stock and Warrants [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 875us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_RestrictedCommonStockAndWarrantsMember 		725us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_RestrictedCommonStockAndWarrantsMember
Securities Sold, But Not Yet Purchased 0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_RestrictedCommonStockAndWarrantsMember 		(4)us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= lts_RestrictedCommonStockAndWarrantsMember
Other Investments [Member]    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities Owned 961us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_OtherInvestmentsMember 		1,948us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecurityOwned
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_OtherInvestmentsMember
Securities Sold, But Not Yet Purchased $ 0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_OtherInvestmentsMember 		$ 0us-gaap_SecurityOwnedAndSoldNotYetPurchasedFairValueSecuritySoldNotYetPurchased
/ us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis
= us-gaap_OtherInvestmentsMember