Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal	$ 9,627,222	$ 9,172,842
Long-term debt	9,453,338	8,983,908
Assets Held For Sale
Debt Instrument [Line Items]
Long-term debt	474,100	515,600
Corporate credit facility
Debt Instrument [Line Items]
Long-term debt	600,000
Convertible and Exchangeable Senior Notes
Debt Instrument [Line Items]
Long-term debt	614,542
Secured debt
Debt Instrument [Line Items]
Long-term debt	8,037,052
Junior Subordinated Notes
Debt Instrument [Line Items]
Long-term debt	201,744
Carrying Value
Debt Instrument [Line Items]
Principal	9,627,222	9,172,842
Premium (discount), net	(91,776)	(93,810)
Deferred financing costs	(82,108)	(95,124)
Long-term debt		8,983,908
Carrying Value \| Corporate credit facility
Debt Instrument [Line Items]
Principal	600,000	0
Premium (discount), net	0	0
Deferred financing costs	0	0
Long-term debt		0
Carrying Value \| Convertible and Exchangeable Senior Notes
Debt Instrument [Line Items]
Principal	616,105	616,105
Premium (discount), net	2,127	2,243
Deferred financing costs	(3,690)	(4,296)
Long-term debt		614,052
Carrying Value \| Secured debt
Debt Instrument [Line Items]
Principal	8,131,000	8,276,620
Premium (discount), net	(15,530)	(17,126)
Deferred financing costs	(78,418)	(90,828)
Long-term debt		8,168,666
Carrying Value \| Junior Subordinated Notes
Debt Instrument [Line Items]
Principal	280,117	280,117
Premium (discount), net	(78,373)	(78,927)
Deferred financing costs	$ 0	0
Long-term debt		$ 201,190

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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