Debt Obligations, net (Schedule of Debt) (Details)		1 Months Ended			12 Months Ended
		Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Aug. 31, 2020 USD ($)	Nov. 30, 2019 USD ($)	Oct. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)
Debt Instrument [Line Items]
Total debt obligations					$ 3,325,450,000	$ 3,436,038,000
Debt discounts and deferred financing costs, net					(38,475,000)	(48,958,000)
Total debt obligations, net	[1]				3,286,975,000	3,387,080,000
Interest costs capitalized					$ 1,900,000	7,500,000	$ 11,300,000
Net Lease Asset
Debt Instrument [Line Items]
Non-recourse debt assumed by buyer			$ 228,000,000.0			228,000,000.0
Senior Term Loan | LIBOR
Debt Instrument [Line Items]
Basis point spread on variable interest rate					1.00%
3.125% senior convertible notes
Debt Instrument [Line Items]
Stated interest rate					3.125%
Secured credit facilities and mortgages
Debt Instrument [Line Items]
Total debt obligations					$ 1,212,950,000	1,212,993,000
Debt discounts and deferred financing costs, net					(6,010,000)
Total debt obligations, net					1,206,940,000
Assets served as collateral					2,100,000,000
Secured credit facilities and mortgages | Revolving Credit Facility
Debt Instrument [Line Items]
Total debt obligations					$ 0	0
Secured credit facilities and mortgages | Revolving Credit Facility | Federal Funds Rate
Debt Instrument [Line Items]
Basis point spread on variable interest rate					0.50%
Secured credit facilities and mortgages | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis point spread on variable interest rate					2.00%
Debt instrument term					1 year
Secured credit facilities and mortgages | Revolving Credit Facility | LIBOR | Minimum
Debt Instrument [Line Items]
Basis point spread on variable interest rate		2.00%			1.00%
Secured credit facilities and mortgages | Revolving Credit Facility | LIBOR | Minimum | Interest Rate Category Two
Debt Instrument [Line Items]
Basis point spread on variable interest rate					2.00%
Secured credit facilities and mortgages | Revolving Credit Facility | LIBOR | Maximum
Debt Instrument [Line Items]
Basis point spread on variable interest rate		2.50%
Secured credit facilities and mortgages | Revolving Credit Facility | LIBOR | Maximum | Interest Rate Category Two
Debt Instrument [Line Items]
Basis point spread on variable interest rate					2.50%
Secured credit facilities and mortgages | Revolving Credit Facility | Base Rate | Minimum
Debt Instrument [Line Items]
Basis point spread on variable interest rate		1.00%
Secured credit facilities and mortgages | Revolving Credit Facility | Base Rate | Minimum | Interest Rate Category One
Debt Instrument [Line Items]
Basis point spread on variable interest rate					1.00%
Secured credit facilities and mortgages | Revolving Credit Facility | Base Rate | Maximum
Debt Instrument [Line Items]
Basis point spread on variable interest rate		1.50%
Secured credit facilities and mortgages | Revolving Credit Facility | Base Rate | Maximum | Interest Rate Category One
Debt Instrument [Line Items]
Basis point spread on variable interest rate					1.50%
Secured credit facilities and mortgages | Senior Term Loan
Debt Instrument [Line Items]
Total debt obligations					$ 491,875,000	491,875,000
Debt instrument, face amount				$ 650,000,000.0
Secured credit facilities and mortgages | Senior Term Loan | Federal Funds Rate
Debt Instrument [Line Items]
Basis point spread on variable interest rate					0.50%
Secured credit facilities and mortgages | Senior Term Loan | LIBOR
Debt Instrument [Line Items]
Basis point spread on variable interest rate				2.75%	2.75%
Secured credit facilities and mortgages | Senior Term Loan | LIBOR | Maximum
Debt Instrument [Line Items]
Basis point spread on variable interest rate					1.75%
Secured credit facilities and mortgages | Mortgages collateralized by net lease assets
Debt Instrument [Line Items]
Total debt obligations					$ 721,075,000	721,118,000
Weighted average interest rate					4.40%
Secured credit facilities and mortgages | Mortgages collateralized by net lease assets | Minimum
Debt Instrument [Line Items]
Stated interest rate					1.69%
Secured credit facilities and mortgages | Mortgages collateralized by net lease assets | Maximum
Debt Instrument [Line Items]
Stated interest rate					7.26%
Unsecured notes
Debt Instrument [Line Items]
Total debt obligations					$ 2,012,500,000	2,123,045,000
Unsecured notes | 6.00% senior notes
Debt Instrument [Line Items]
Total debt obligations					$ 0	$ 110,545,000
Stated interest rate					6.00%	6.00%
Unsecured notes | 5.25% senior notes
Debt Instrument [Line Items]
Total debt obligations					$ 0	$ 400,000,000
Stated interest rate					5.25%			5.25%
Debt instrument, face amount								$ 400,000,000.0
Unsecured notes | 3.125% senior convertible notes
Debt Instrument [Line Items]
Total debt obligations					$ 287,500,000	287,500,000
Total debt obligations, net					$ 275,100,000	$ 268,700,000
Stated interest rate					3.125%	3.125%				3.125%
Convertible debt conversion ratio (in shares per par value)					0.07025
Convertible debt conversion price (in dollars per share) | $ / shares					$ 14.23
Liability component of convertible debt										$ 34,000,000.0	$ 221,800,000
Equity component of convertible debt										3,400,000	$ 22,500,000
Debt instrument, face amount										$ 37,500,000
Unamortized discount					$ 10,200,000	$ 15,500,000
Contractual interest					9,000,000.0	9,000,000.0	9,000,000.0
Amortization of debt discount					$ 5,200,000	$ 5,000,000.0	$ 4,700,000
Effective interest rate					5.20%	5.20%	5.20%
Unsecured notes | 4.75% senior notes
Debt Instrument [Line Items]
Total debt obligations					$ 775,000,000	$ 775,000,000
Stated interest rate		4.75%			4.75%				4.75%
Debt instrument, face amount		$ 675,000,000.0							$ 100,000,000.0
Effective interest rate									4.29%
Unsecured notes | 4.25% senior notes
Debt Instrument [Line Items]
Total debt obligations					$ 550,000,000	$ 550,000,000
Stated interest rate					4.25%	4.25%
Debt instrument, face amount						$ 550,000,000.0
Unsecured notes | 5.5% senior notes
Debt Instrument [Line Items]
Total debt obligations					$ 400,000,000	0
Stated interest rate					5.50%
Other debt obligations | Trust preferred securities
Debt Instrument [Line Items]
Total debt obligations					$ 100,000,000	$ 100,000,000
Other debt obligations | Trust preferred securities | LIBOR
Debt Instrument [Line Items]
Basis point spread on variable interest rate					1.50%

[1] Refer to Note 2 for details on the Company's consolidated variable interest entities ("VIEs").