Real Estate (Dispositions) (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) net_lease_asset property
Other Dispositions by Property Type
Proceeds			$ 48,415	$ 329,971	$ 411,786
Income from sales of real estate		$ 24,500	6,318	236,623	126,004
Impairment of assets			7,827	13,419	147,108
Total
Other Dispositions by Property Type
Proceeds			48,300	555,500	407,600
Income from sales of real estate			6,300	236,600	126,000
Operating Properties
Other Dispositions by Property Type
Proceeds			5,900	86,100	327,900
Income from sales of real estate			200	11,900	$ 81,000
Aggregate carrying value of property sold				73,100
Number of properties sold | property					10
Operating Properties | Income from sales of real estate
Other Dispositions by Property Type
Income from sales of real estate				11,900	$ 81,000
Net Lease
Other Dispositions by Property Type
Proceeds			42,400	469,400	79,700
Income from sales of real estate			6,100	224,700	$ 45,000
Aggregate carrying value of property sold				220,400
Number of properties sold | net_lease_asset					5
Non-recourse debt assumed by buyer	$ 228,000			228,000
Net Lease | Income from sales of real estate
Other Dispositions by Property Type
Income from sales of real estate				$ 219,700	$ 45,000
Net Lease Asset
Other Dispositions by Property Type
Proceeds			7,500
Impairment of assets			$ 1,700
Operating Properties, Noncontrolling Interest
Other Dispositions by Property Type
Income from sales of real estate					$ 9,800