Quarterly report pursuant to Section 13 or 15(d)

Acquisitions (Purchase Price Allocation) (Details)

v2.4.1.9
Acquisitions (Purchase Price Allocation) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Jan. 02, 2015
Business Acquisition [Line Items]      
Goodwill $ 124,734us-gaap_Goodwill $ 115,238us-gaap_Goodwill  
Securities Service Network, Inc. (SSN)      
Business Acquisition [Line Items]      
Cash     8,081us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Securities owned, at fair value     158lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsSecuritiesOwnedatFairValue
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Receivables from clearing broker     630lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsReceivablesfromClearingBroker
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Other receivables, net     2,611lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsOtherReceivables
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Fixed assets, net     57us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Notes receivable     225us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Identifiable intangible assets     30,901us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Goodwill     8,798us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Other assets     714us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Total assets acquired 52,175us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
  52,175us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Commissions and fees payable     3,462lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesCommissionsandFeesPayable
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Deferred income     44lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNoncurrentLiabilitiesDeferredIncome
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Accounts payable and accrued liabilities     1,382lts_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedAccountsPayableandAccrueLiabilities
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Total liabilities assumed 4,888us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
  4,888us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
Total purchase price $ 47,287us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember
  $ 47,287us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet
/ us-gaap_BusinessAcquisitionAxis
= lts_SecuritiesServiceNetworkInc.SSNMember