Real Estate Investments and Related Intangibles - Property Dispositions and Real Estate Assets Held for Sale Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) property	Jun. 30, 2017 USD ($) property	Dec. 31, 2017 property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds after debt assumptions and closing costs	$ 180,723	$ 301,320
Proceeds from disposition of discontinued operations	$ 123,925	$ 0
Number of properties classified held for sale | property	11		30
Carrying value of properties classified as held for sale	$ 29,900
Consolidated Property Dispositions, 2018 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property	77
Number of properties secured by each non-recourse loan | property	1
Aggregate proceeds	$ 181,600
Company's share of proceeds	175,500
Proceeds after debt assumptions and closing costs	175,100
Gain (loss) related to sale	$ 24,200
Red Lobster [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property	11	20
Consolidated Property Dispositions, 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property		87
Number of properties secured by each non-recourse loan | property		4
Number of real estate properties disposed in non monetary exchange | property		15
Aggregate proceeds		$ 439,200
Company's share of proceeds		425,600
Proceeds after debt assumptions and closing costs		301,300
Debt assumed		66,000
Gain related to sale of unconsolidated entities		55,600
Unconsolidated Property Dispositions, 2018 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Company's share of proceeds	$ 17,100
Number of disposed properties owned by unconsolidated joint ventures | property	1
Proceeds from disposition of discontinued operations	$ 34,100
Proceeds from after debt repayments and closing costs	5,600
Debt repayments	20,400
Net gain (loss) on sale of properties	700
Property Disposition, 2018 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on sale of properties	$ (1,100)	(500)
Foreign Tax Authority [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Tax provision for the gain on sale of property		$ 1,700