Quarterly Results (Unaudited) (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
Schedule of quarterly income statement including basic and diluted earning per share
Total revenues from continuing operations	$ 146,564	$ 126,986	$ 135,689	$ 130,085	$ 118,933	$ 132,786	$ 130,856	$ 95,241	$ 539,324	$ 477,816	$ 483,686
Operating (loss) income from continuing operations	16,661	7,417	16,087	14,547	8,297	13,804	15,154	(1,787)	54,712	35,468	24,608
Net income (loss)	$ 91,648	$ 233	$ 1,198	$ 3,229	$ 1,715	$ 3,090	$ 5,883	$ (18,398)	$ 96,308	$ (7,710)	$ (12,579)
Net (loss) income per common share:
Basic	$ 5.23	$ 0.01	$ 0.07	$ 0.25	$ 0.14	$ 0.24	$ 0.46	$ (1.44)	$ 6.11	$ (0.60)	$ (0.99)
Diluted	$ 5.12	$ 0.01	$ 0.07	$ 0.25	$ 0.14	$ 0.24	$ 0.46	$ (1.44)	$ 5.99	$ (0.60)	$ (0.99)