Debt (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 6,221,920	$ 6,122,413
Less current portion	275,661	235,604
Long-term debt	5,946,259	5,886,809
Mortgage Notes Payable [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	3,329,740	3,246,513
Unamortized debt discount	$ 1,300	$ 3,300
Maturity date, start	Dec. 31, 2017
Maturity date, end	Dec. 31, 2047
Weighted average interest rate	4.58%	4.51%
Capital Lease Obligations [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 2,493,210	$ 2,489,588
Maturity date, start	Dec. 31, 2031
Weighted average interest rate	8.07%	8.11%
Convertible Debt [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 285,189	$ 281,902
Principal	316,300	316,300
Unamortized debt discount	$ 31,100	$ 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	$ 15,353	$ 24,105
Maturity date, start	Dec. 31, 2019
Maturity date, end	Dec. 31, 2032
Weighted average interest rate	7.76%	4.84%
Notes Payable, Insurance Premiums [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 17,677	$ 0
Maturity date, start	Dec. 31, 2016
Weighted average interest rate	2.94%
Other Notes Payable [Member]
Long-Term Debt, Capital and Financing Leases and Financing Obligations [Line Items]
Debt	$ 80,751	$ 80,305
Maturity date, start	Dec. 31, 2016
Maturity date, end	Dec. 31, 2020
Weighted average interest rate	5.24%	5.16%