Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Taxes
Income tax expense recognized on pre-tax earnings	$ 46	$ 1,528
Pre-tax earnings	668	3,796
Effective tax rate (as a percent)	6.90%	40.30%
Effective tax rate before benefit from federal income tax credit programs (as a percent)	37.70%
Discrete benefit for retroactive extension of tax credit programs	$ 206