Quarterly report pursuant to Section 13 or 15(d)

Goodwill (Changes To The Carrying Amount) (Detail)

v2.4.1.9
Goodwill (Changes To The Carrying Amount) (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Goodwill [Roll Forward]  
Beginning balance $ 115,238us-gaap_Goodwill
Benefit applied to reduce goodwill (19)lts_BenefitAppliedToReduceGoodwill
Adjustment related to allocation of Highland purchase price 717us-gaap_GoodwillPeriodIncreaseDecrease
Business acquisitions 8,798us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
Ending balance 124,734us-gaap_Goodwill
Ladenburg  
Goodwill [Roll Forward]  
Beginning balance 301us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_LadenburgThalmannAndCoIncMember
Benefit applied to reduce goodwill 0lts_BenefitAppliedToReduceGoodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_LadenburgThalmannAndCoIncMember
Adjustment related to allocation of Highland purchase price 0us-gaap_GoodwillPeriodIncreaseDecrease
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_LadenburgThalmannAndCoIncMember
Business acquisitions 0us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_LadenburgThalmannAndCoIncMember
Ending balance 301us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_LadenburgThalmannAndCoIncMember
Independent brokerage and advisory services  
Goodwill [Roll Forward]  
Beginning balance 103,422us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_IndependentBrokerageAndAdvisoryServicesMember
Benefit applied to reduce goodwill (19)lts_BenefitAppliedToReduceGoodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_IndependentBrokerageAndAdvisoryServicesMember
Adjustment related to allocation of Highland purchase price 0us-gaap_GoodwillPeriodIncreaseDecrease
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_IndependentBrokerageAndAdvisoryServicesMember
Business acquisitions 8,798us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_IndependentBrokerageAndAdvisoryServicesMember
Ending balance 112,201us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_IndependentBrokerageAndAdvisoryServicesMember
Insurance Brokerage [Member]  
Goodwill [Roll Forward]  
Beginning balance 11,515us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_InsuranceBrokerageMember
Benefit applied to reduce goodwill 0lts_BenefitAppliedToReduceGoodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_InsuranceBrokerageMember
Adjustment related to allocation of Highland purchase price 717us-gaap_GoodwillPeriodIncreaseDecrease
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_InsuranceBrokerageMember
Business acquisitions 0us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_InsuranceBrokerageMember
Ending balance $ 12,232us-gaap_Goodwill
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= lts_InsuranceBrokerageMember