Fair Value of Financial Instruments (Recurring) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Cash and cash equivalents	$ 72,031	$ 99,090
Restricted cash	17,943	10,926
Equity Securities		22,709
Total Financial Assets	89,974	132,725
Financial Liabilities:
Total debt	1,622,811	1,315,473
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	72,031	99,090
Restricted cash	0	0
Equity Securities		22,709
Total Financial Assets	72,031	121,799
Financial Liabilities:
Total debt	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	17,943	10,926
Equity Securities		0
Total Financial Assets	17,943	10,926
Financial Liabilities:
Total debt	1,622,811	1,315,473
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Equity Securities		0
Total Financial Assets	0	0
Financial Liabilities:
Total debt	0	0
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset for interest rate swap agreements	5,400
Liability for interest rate swap agreements	(2,300)	(4,400)
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset for interest rate swap agreements	5,392
Liability for interest rate swap agreements	(2,283)	(4,370)
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset for interest rate swap agreements	0
Liability for interest rate swap agreements	0	0
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset for interest rate swap agreements	5,392
Liability for interest rate swap agreements	(2,283)	(4,370)
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset for interest rate swap agreements	0
Liability for interest rate swap agreements	$ 0	$ 0