Annual report pursuant to Section 13 and 15(d)

Share-Based and Cash-Based Incentive Compensation - Summary of Compensation Expense under Share-Based Payment Arrangements and Related Tax Benefit (Details)

v2.4.1.9
Share-Based and Cash-Based Incentive Compensation - Summary of Compensation Expense under Share-Based Payment Arrangements and Related Tax Benefit (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation $ 14,744us-gaap_ShareBasedCompensation $ 11,525us-gaap_ShareBasedCompensation $ 12,398us-gaap_ShareBasedCompensation
Tax benefit computed at the statutory rate 5,160us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 4,034us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 4,339us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Restricted Shares      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation 369us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
397us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
399us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
Restricted Stock Units (RSUs)      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation 13,150us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
11,128us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
11,999us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
Common Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation $ 1,225us-gaap_ShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember