Income Taxes - Significant Components of Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current, Federal	$ 109,893	$ 94,007	$ 75,522
Current, State	15,482	13,438	11,852
Current, Foreign	109	805	669
Total current provision	125,484	108,250	88,043
Deferred, Federal	5,987	28,469	27,348
Deferred, State	1,440	3,723	5,375
Deferred, Foreign	(58)	55
Total deferred provision	7,369	32,247	32,723
Total tax provision	$ 132,853	$ 140,497	$ 120,766