Income Taxes - Summary of Provisions for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current:
Federal	$ 28,654	$ 33,006	$ 13,723
State	4,695	4,514	3,754
Total Current	33,349	37,520	17,477
Deferred:
Federal	559	7,543	1,602
State	(314)	1,145	708
Total Deferred	245	8,688	2,310
Provisions for income taxes	$ 33,594	$ 46,208	$ 19,787