Fair Value of Financial Instruments (Recurring) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	$ 148,858	$ 259,266
Restricted cash	0	0
Equity securities	22,168	20,884
Total Financial Assets	171,026	280,150
Financial Liabilities:
Total debt	0	0
Total Financial Liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	22,117	22,044
Equity securities	0	0
Total Financial Assets	22,117	22,044
Financial Liabilities:
Total debt	899,258	828,990
Total Financial Liabilities	899,258	828,990
Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Equity securities	0	0
Total Financial Assets	0	0
Financial Liabilities:
Total debt	0	0
Total Financial Liabilities	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Assets:
Cash and cash equivalents	148,858	259,266
Restricted cash	22,117	22,044
Equity securities	22,168	20,884
Total Financial Assets	193,143	302,194
Financial Liabilities:
Total debt	899,258	828,990
Total Financial Liabilities	899,258	828,990
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Asset for interest rate swap agreements		0
Derivative Assets	0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Asset for interest rate swap agreements		(5,078)
Derivative Assets	6,486
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Asset for interest rate swap agreements		0
Derivative Assets	0
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives:
Asset for interest rate swap agreements		(5,078)
Derivative Assets	$ 6,486