Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, 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
Reclassification adjustments to the previously issued financial statements
Revenues	$ 52,107	$ 39,895	$ 42,270	$ 33,932	$ 46,366	$ 39,700	$ 40,350	$ 37,552	$ 168,204	$ 163,968	$ 174,402
Income (loss) from continuing operations, net of income taxes	8,576	2,200	4,282	(1,864)	32,525	1,519	3,542	(1,719)	13,194	35,867	9,604
Income from discontinued operations, net of income taxes					577	(75)	74	(8)		568	142
Net income (loss)	$ 8,576	$ 2,200	$ 4,282	$ (1,864)	$ 33,102	$ 1,444	$ 3,616	$ (1,727)	$ 13,194	$ 36,435	$ 9,746
Net income (loss) per share:
From continuing operations	$ 0.97	$ 0.25	$ 0.48	$ (0.21)	$ 3.68	$ 0.17	$ 0.40	$ (0.20)	$ 1.49	$ 4.06	$ 1.09
From discontinued operations					$ 0.07	$ (0.01)	$ 0.01			$ 0.07	$ 0.02
Net Income (loss)	$ 0.97	$ 0.25	$ 0.48	$ (0.21)	$ 3.75	$ 0.16	$ 0.41	$ (0.20)	$ 1.49	$ 4.13	$ 1.11
Net income per share assuming dilution:
From continuing operations	$ 0.96	$ 0.25	$ 0.48	$ (0.21)	$ 3.65	$ 0.17	$ 0.40	$ (0.20)	$ 1.47	$ 4.03	$ 1.09
From discontinued operations					$ 0.06	$ (0.01)	$ 0.01			$ 0.06	$ 0.01
Net income (loss)	$ 0.96	$ 0.25	$ 0.48	$ (0.21)	$ 3.71	$ 0.16	$ 0.41	$ (0.20)	$ 1.47	$ 4.09	$ 1.10