Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	$ 535,000		$ 418,900		$ 267,300		$ 266,600		$ 254,800		$ 256,200		$ 248,500		$ 243,400		$ 1,487,836	$ 1,002,836	$ 940,874
Operating income (loss)	69,800		(15,200)		17,900		31,900		22,900		32,700		38,800		42,300		104,387	136,695	127,266
Income (loss) from continuing operations	8,600		(47,100)		(7,100)		(87,800)		(31,100)		6,700		13,200		(2,000)		(133,381)	(13,237)	28,903
Income (loss) from discontinued operations	6,400		(133,300)		2,000		2,400		(11,300)		(7,100)		(1,200)		1,000		(122,540)	(18,568)	(31,442)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	15,000		(180,400)		(5,100)		(85,400)		(42,400)		(400)		12,000		(1,000)		(255,921)	(31,805)	(2,539)
Loss attributable to non-controlling interest	0		0		0		0		0		0		0		0		(51)	0	0
Net income (loss)	$ 15,000		$ (180,400)		$ (5,100)		$ (85,400)		$ (42,400)		$ (400)		$ 12,000		$ (1,000)		$ (255,870)	$ (31,805)	$ (2,539)
Income (loss) from continuing operations	$ 0.15	[1]	$ (0.80)	[1]	$ (0.12)	[1]	$ (1.50)	[1]	$ (0.53)	[1]	$ 0.11	[1]	$ 0.21	[1]	$ (0.03)	[1]	$ (2.27)	$ (0.22)	$ 0.47
Income (loss) from discontinued operations, net of income taxes	$ 0.11	[1]	$ (2.27)	[1]	$ 0.03	[1]	$ 0.04	[1]	$ (0.19)	[1]	$ (0.11)	[1]	$ (0.02)	[1]	$ 0.01	[1]	$ (2.09)	$ (0.30)	$ (0.51)
Net income (loss)- basic	$ 0.26	[1]	$ (3.07)	[1]	$ (0.09)	[1]	$ (1.46)	[1]	$ (0.72)	[1]	$ 0.00	[1]	$ 0.19	[1]	$ (0.02)	[1]	$ (4.36)	$ (0.52)	$ (0.04)
Income (loss) from continuing operations	$ 0.14	[1]	$ (0.80)	[1]	$ (0.12)	[1]	$ (1.50)	[1]	$ (0.53)	[1]	$ 0.11	[1]	$ 0.21	[1]	$ (0.03)	[1]	$ (2.27)	$ (0.22)	$ 0.46
Income (loss) from discontinued operations, net of income taxes	$ 0.11	[1]	$ (2.27)	[1]	$ 0.03	[1]	$ 0.04	[1]	$ (0.19)	[1]	$ (0.11)	[1]	$ (0.02)	[1]	$ 0.01	[1]	$ (2.09)	$ (0.30)	$ (0.50)
Net income (loss)- diluted	$ 0.25	[1]	$ (3.07)	[1]	$ (0.09)	[1]	$ (1.46)	[1]	$ (0.72)	[1]	$ 0.00	[1]	$ 0.19	[1]	$ (0.02)	[1]	$ (4.36)	$ (0.52)	$ (0.04)

[1] Net income (loss) per share calculations for each quarter is based on the weighted average number of shares outstanding during the respective periods; accordingly, the sum of the quarters may not equal the full-year income (loss) per share.