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Shareholders' Equity - Narrative (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
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3 Months Ended |
94 Months Ended |
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Mar. 31, 2015
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Mar. 31, 2014
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Mar. 31, 2015
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Nov. 30, 2014
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Oct. 31, 2011
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Mar. 31, 2007
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| Capital Unit [Line Items] |
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| Shares authorized for repurchase |
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2,500,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
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| Shares authorized for additional repurchase |
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10,000,000lts_StockRepurchaseProgramNumberOfAdditionalSharesAuthorizedToBeRepurchased
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5,000,000lts_StockRepurchaseProgramNumberOfAdditionalSharesAuthorizedToBeRepurchased
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| Shares repurchased, shares |
403,841us-gaap_StockRepurchasedDuringPeriodShares
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6,999,993us-gaap_StockRepurchasedDuringPeriodShares
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| Shares repurchased, value |
$ 1,589us-gaap_StockRepurchasedDuringPeriodValue
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$ 17,213us-gaap_StockRepurchasedDuringPeriodValue
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| Options forfeited |
55,712us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
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| Unrecognized compensation cost for stock based compensation |
17,083us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
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17,083us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
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| Unrecognized compensation cost for stock based compensation, period of recognition |
2 years 3 months 20 days
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| Purchase of shares |
489,584us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
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| Intrinsic value of options exercised |
1,296us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
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| Share-based compensation |
3,260us-gaap_ShareBasedCompensation
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1,927us-gaap_ShareBasedCompensation
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| Grands in 2015 [Member] |
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| Capital Unit [Line Items] |
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| Unrecognized compensation cost for stock based compensation |
3,531us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_PlanNameAxis
= lts_Grandsin2015Member
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3,531us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_PlanNameAxis
= lts_Grandsin2015Member
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| Unrecognized compensation cost for stock based compensation, period of recognition |
3 years 9 months 2 days
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| Restricted shares |
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| Capital Unit [Line Items] |
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| Unrecognized compensation cost for stock based compensation |
4,111us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
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4,111us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
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| Unrecognized compensation cost for stock based compensation, period of recognition |
3 years 9 months 7 days
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| Share-based compensation |
1,667us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
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| Restricted shares | Grands in 2015 [Member] |
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| Capital Unit [Line Items] |
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| Unrecognized compensation cost for stock based compensation, period of recognition |
3 years 8 months 27 days
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| Options |
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| Capital Unit [Line Items] |
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| Share-based compensation |
$ 1,593us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
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