Income Taxes (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Taxes
Effective tax rate (as a percent)	10.30%	44.70%
Federal statutory tax rate (as a percent)	35.00%	35.00%
Liability for an uncertain tax position	$ 800,000
Interest or penalties related to uncertain tax positions	200,000	0
Change in unrecognized tax benefits
Balance at beginning of period	3,797,000	100,000
Additions for tax positions related to prior periods	835,000
Balance at end of period	4,632,000	100,000
Deferred tax assets, operating loss carryforwards
Tax-effected carrying value of federal NOL carryforwards	32,200,000
Tax-effected carrying value of state NOL carryforwards	$ 5,300,000