Income Taxes - Provision for Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current tax expense (benefit):
Federal	$ (566)	$ 3,539	$ 4,194
State	86	495	508
Current tax expense (benefit)	(480)	4,034	4,702
Deferred tax expense (benefit):
Federal	2,058	(584)	1,987
State	121	(390)	2,126
Deferred tax expense (benefit)	2,179	(974)	4,113
Income tax provision	$ 1,699	$ 3,060	$ 8,815