Real Estate Investments and Related Intangibles - Property Dispositions and Real Estate Assets Held for Sale Narrative (Details)		12 Months Ended
	Jun. 27, 2017 property	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($) property	Dec. 31, 2015 USD ($) property joint_venture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property				228
Number of properties owned by consolidated joint ventures disposed of | property		1
Number of properties secured by each non-recourse loan | property	4	6
Proceeds after debt assumptions and closing costs		$ 445,525,000	$ 1,000,700,000	$ 1,009,107,000
Goodwill allocated to dispositions and held for sale assets			$ 73,200,000
Number of properties classified held for sale | property		30	1
Carrying value of properties classified as held for sale		$ 38,300,000
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		$ 1,700,000
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		137
Aggregate proceeds		$ 594,900,000
Company's share of proceeds		574,400,000
Proceeds after debt assumptions and closing costs		445,500,000
Debt assumed		66,000,000
Gain (loss) related to sale		$ 64,700,000
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		31	70
Number of real estate properties disposed in non monetary exchange | property		15
Consolidated Property Dispositions, 2016 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property			301
Aggregate proceeds			$ 1,080,000,000
Company's share of proceeds			1,040,000,000
Proceeds after debt assumptions and closing costs			958,400,000
Debt assumed			55,000,000
Gain related to sale of unconsolidated entities			45,700,000
Goodwill allocated to dispositions and held for sale assets			67,800,000
Unconsolidated Property Dispositions, 2016 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Company's share of proceeds			102,100,000
Gain related to sale of unconsolidated entities			$ 10,200,000
Number of disposed properties owned by unconsolidated joint ventures | property			1
Net proceeds			$ 113,500,000
Proceeds from after debt repayments and closing costs			42,300,000
Debt repayments			$ 57,000,000
Consolidated Property Disposition, 2015 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property				2
Number of properties owned by consolidated joint ventures disposed of | property				1
Aggregate proceeds				$ 1,400,000,000
Company's share of proceeds				69,800,000
Proceeds after debt assumptions and closing costs				966,100,000
Gain (loss) related to sale				(69,100,000)
Gain related to sale of unconsolidated entities				6,700,000
Net proceeds				77,500,000
Proceeds from after debt repayments and closing costs				43,000,000
Goodwill included in sale				$ 96,700,000
Unconsolidated Property Dispositions, 2015 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of disposed properties owned by unconsolidated joint ventures | joint_venture				3
Property Dispositions, 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill allocated to dispositions and held for sale assets		$ 0
Number of properties classified held for sale | property			11
Net loss on sale of properties		$ 3,100,000
Property Dispositions, 2016 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill allocated to dispositions and held for sale assets			$ 3,200,000
Net loss on sale of properties			$ 200,000