Stock Compensation Plans - Stock-Based Compensation Expense and Related Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 10,857	$ 10,127	$ 16,798	$ 16,101
Less: tax benefit	(3,345)	(3,114)	(5,071)	(5,021)
Total stock-based compensation expense, after tax	7,512	7,013	11,727	11,080
Equity-based awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	9,338	9,527	14,034	14,050
Liability-based awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 1,519	$ 600	$ 2,764	$ 2,051