Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of income before taxes
United States									$ (1,468)	$ 27,152	$ 23,617
Foreign									222	1,024	1,784
Income before income taxes	(15,994)	4,773	6,958	3,017	5,366	8,942	8,074	5,794	(1,246)	28,176	25,401
Current provision:
U.S. federal									748	6,202	5,958
Foreign									233	292	682
State									(11,830)	1,678	1,238
Total current									(10,849)	8,172	7,878
Deferred provision:
U.S. federal									6,069	2,547	1,635
Foreign									(11)	5	(96)
State									1,171	(24)	353
Total deferred									7,229	2,528	1,892
Income tax (benefit) expense	$ (10,140)	$ 2,504	$ 2,801	$ 1,215	$ 1,766	$ 3,427	$ 3,235	$ 2,272	$ (3,620)	$ 10,700	$ 9,770