Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																							3 Months Ended
	Mar. 31, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2012 Interest Rate Swap [Member] Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Mar. 31, 2012 Assets, Discontinued Operations [Member] Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2013 Property and equipment [Member] Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2012 Property and equipment [Member] Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of Disposal Group, Including Discontinued Operation, Current		$ 791			$ 794		$ 794		$ 0		$ 0
Fair Value, Nonrecurring Basis, Asset, Gain (Loss) Included in Earnings	15,939																							13,915	844	2,024
Property and equipment, net		186,399	186,617	0	0	0	0	0	0	0	0
Financial Assets:
Cash and cash equivalents												125,559	148,858	0	0	125,559	148,858
Restricted cash												0	0	22,158	22,117	22,158	22,117
Equity securities												21,871	22,168	0	0	21,871	22,168
Total Financial Assets				794		794		0		0		147,430	171,026	22,158	22,117	169,588	193,143
Financial Liabilities:
Total debt												0	0	891,647	899,258	891,647	899,258
Total Financial Liabilities												0	0	891,647	899,258	891,647	899,258
Derivative Assets																		0		5,593
Interest rate swap agreements																			$ 0		$ (6,486)	$ 5,593	$ 6,486