Debt - Schedule of Debt (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Debt [Roll Forward]
Total debt, Beginning balance	$ 8,059,802
Debt Issuances, Net	2,316,184
Repayments, Extinguishment and Assumptions, Net	(4,011,480)
Accretion and Amortization	2,742
Total debt, Ending balance	6,367,248
Mortgages and Other Debt [Member]
Debt [Roll Forward]
Total debt, Beginning balance	3,111,985
Debt Issuances, Net	3,085
Repayments, Extinguishment and Assumptions, Net	(427,352)
Accretion and Amortization	(16,612)
Total debt, Ending balance	2,671,106
Mortgage Notes Payable [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	3,039,882
Net premiums (discount), Beginning balance	59,402
Deferred costs, Beginning balance	(21,020)
Debt Issuances	3,112
Debt Issuances, Deferred Costs	(27)
Repayments, Extinguishment and Assumptions	(413,045)
Repayments, Extinguishment and Assumptions, Net Premiums (Discount)	(2,313)
Repayments, Extinguishment and Assumptions, Deferred costs	522
(Accretion) and Amortization, (Premiums) Discount	(20,338)
(Accretion) and Amortization, Deferred costs	3,892
Outstanding balance, Ending balance	2,629,949
Net premiums (discount), Ending balance	36,751
Deferred costs, Ending balance	(16,633)
Other Debt [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	33,463
Net premiums (discount), Beginning balance	258
Repayments, Extinguishment and Assumptions	(12,516)
(Accretion) and Amortization, (Premiums) Discount	(166)
Outstanding balance, Ending balance	20,947
Net premiums (discount), Ending balance	92
Corporate Bonds [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	2,550,000
Net premiums (discount), Beginning balance	(2,745)
Deferred costs, Beginning balance	(10,922)
Total debt, Beginning balance	2,536,333
Debt Issuances	1,000,000
Debt Issuances, Deferred Costs	(17,137)
Debt Issuances, Net	982,863
Repayments, Extinguishment and Assumptions	(1,300,000)
Repayments, Extinguishment and Assumptions, Net Premiums (Discount)	73
Repayments, Extinguishment and Assumptions, Deferred costs	1,898
Repayments, Extinguishment and Assumptions, Net	(1,298,029)
(Accretion) and Amortization, (Premiums) Discount	735
(Accretion) and Amortization, Deferred costs	4,322
Accretion and Amortization	5,057
Outstanding balance, Ending balance	2,250,000
Net premiums (discount), Ending balance	(1,937)
Deferred costs, Ending balance	(21,839)
Total debt, Ending balance	2,226,224
Convertible Debt [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	1,000,000
Net premiums (discount), Beginning balance	(17,779)
Deferred costs, Beginning balance	(19,327)
Total debt, Beginning balance	962,894
(Accretion) and Amortization, (Premiums) Discount	4,885
(Accretion) and Amortization, Deferred costs	5,561
Accretion and Amortization	10,446
Outstanding balance, Ending balance	1,000,000
Net premiums (discount), Ending balance	(12,894)
Deferred costs, Ending balance	(13,766)
Total debt, Ending balance	973,340
Credit Facility [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	1,460,000
Deferred costs, Beginning balance	(11,410)
Total debt, Beginning balance	1,448,590
Debt Issuances	1,033,000
Debt Issuances, Deferred Costs	0
Debt Issuances, Net	1,033,000
Repayments, Extinguishment and Assumptions	(1,993,000)
Repayments, Extinguishment and Assumptions, Deferred costs	4,313
Repayments, Extinguishment and Assumptions, Net	(1,988,687)
(Accretion) and Amortization, Deferred costs	3,675
Accretion and Amortization	3,675
Outstanding balance, Ending balance	500,000
Deferred costs, Ending balance	(3,422)
Total debt, Ending balance	496,578
2016 Term Loan [Member]
Debt [Roll Forward]
Outstanding balance, Beginning balance	0
Deferred costs, Beginning balance	0
Total debt, Beginning balance	0
Debt Issuances	300,000
Debt Issuances, Deferred Costs	(2,764)
Debt Issuances, Net	297,236
Repayments, Extinguishment and Assumptions	(300,000)
Repayments, Extinguishment and Assumptions, Deferred costs	2,588
Repayments, Extinguishment and Assumptions, Net	(297,412)
(Accretion) and Amortization, Deferred costs	176
Accretion and Amortization	176
Outstanding balance, Ending balance	0
Deferred costs, Ending balance	0
Total debt, Ending balance	$ 0