Annual report pursuant to Section 13 and 15(d)

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

v2.4.0.6
Summary of Compensation Expense under Share-Based Payment Arrangements and Related Tax Benefit (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation $ 12,398 $ 9,710 $ 5,533
Tax benefit computed at the statutory rate 4,339 3,399 1,937
Restricted Stock
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation 399 2,377 3,469
Restricted Stock Units (RSUs)
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation $ 11,999 $ 7,333 $ 2,064