Debt (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 6,130,894	$ 6,122,413
Less current portion	265,376	235,604
Long-term debt	5,865,518	5,886,809
Mortgage Notes Payable [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	3,240,934	3,246,513
Unamortized debt discount	$ 2,400	$ 3,300
Maturity date, start	Dec. 31, 2017
Maturity date, end	Dec. 31, 2047
Weighted average interest rate	4.58%	4.51%
Capital and Financing Lease Obligations [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 2,491,534	$ 2,489,588
Maturity date, start	Dec. 31, 2031
Weighted average interest rate	8.06%	8.11%
Convertible Debt [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 291,936	$ 281,902
Principal	316,300	316,300
Unamortized debt discount	$ 24,300	$ 34,300
Maturity date, start	Jun. 30, 2018
Weighted average interest rate	2.75%	2.75%
Construction Financing [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 24,202	$ 24,105
Maturity date, start	Dec. 31, 2019
Maturity date, end	Dec. 31, 2032
Weighted average interest rate	7.77%	4.84%
Notes Payable, Insurance Premiums [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 4,452	$ 0
Maturity date, start	Nov. 30, 2016
Weighted average interest rate	2.94%
Other Notes Payable [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 77,836	$ 80,305
Maturity date, start	Dec. 31, 2016
Maturity date, end	Dec. 31, 2020
Weighted average interest rate	5.29%	5.16%