Federal and State Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current
Federal	$ 12,718	$ 8,836	$ 3,724
State	5,522	4,191	3,481
Total current tax expense	18,240	13,027	7,205
Deferred
Federal	708	(11,256)	115
State	129	(2,052)	23
Total deferred tax expense (benefit)	837	(13,308)	138
Total income tax expense (benefit)	$ 19,077	$ (281)	$ 7,343