Fair Value of Financial Instruments (Recurring) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	$ 104,677	$ 134,419
Restricted cash	0	0
Equity securities	22,264	22,220
Total Financial Assets	126,941	156,639
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	12,360	12,050
Equity securities	0	0
Total Financial Assets	12,360	12,050
Financial Liabilities:
Total debt	1,323,201	869,232
Total Financial Liabilities	1,323,201	869,232
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	104,677	134,419
Restricted cash	12,360	12,050
Equity securities	22,264	22,220
Total Financial Assets	139,301	168,689
Financial Liabilities:
Total debt	1,323,201	869,232
Total Financial Liabilities	1,323,201	869,232
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Liability for interest rate swap agreements	0	0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Liability for interest rate swap agreements	3,781	4,020
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Liability for interest rate swap agreements	0	0
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives:
Liability for interest rate swap agreements	$ 3,781	$ 4,020