Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current:
Federal	$ 45,112	$ 96,449	$ 69,911
State	8,004	12,468	8,556
Deferred:
Federal	21,492	6,352	23,474
State	3,548	1,119	4,293
Total	$ 78,156	$ 116,388	$ 106,234