Fair Value Measurements (Details)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of domestic regions	2
Assets:
Interest Rate Derivative Assets, at Fair Value	$ 31,000
Total	4,397,000	$ 32,587,000
Liabilities:
Interest rate derivative financial instruments	31,153,000	28,653,000
Total	31,153,000	28,653,000
Fair Value, Inputs, Level 1 [Member]
Assets:
Interest Rate Derivative Assets, at Fair Value	0
Total	0	0
Liabilities:
Interest rate derivative financial instruments	0	0
Total	0	0
Level 2 [Member]
Assets:
Interest Rate Derivative Assets, at Fair Value	31,000
Total	4,397,000	32,587,000
Liabilities:
Interest rate derivative financial instruments	31,153,000	28,653,000
Total	31,153,000	28,653,000
Investments [Member]
Assets:
Investments, Fair Value Disclosure	4,235,000	12,283,000
Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Investments, Fair Value Disclosure	0	0
Investments [Member] | Level 2 [Member]
Assets:
Investments, Fair Value Disclosure	4,235,000	12,283,000
Demand Obligation [Member]
Assets:
Investments, Fair Value Disclosure	131,000	20,304,000
Demand Obligation [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Investments, Fair Value Disclosure	0	0
Demand Obligation [Member] | Level 2 [Member]
Assets:
Investments, Fair Value Disclosure	$ 131,000	$ 20,304,000