Real Estate Investments - Property Dispositions and Held for Sale Assets Narrative (Details)	3 Months Ended
	Mar. 31, 2017 USD ($) property	Mar. 31, 2016 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property	0
Proceeds after debt assumptions and closing costs	$ 195,730,000	$ 176,137,000
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	50
Aggregate proceeds	$ 210,600,000
Company's share of proceeds	200,800,000
Proceeds after debt assumptions and closing costs	195,700,000
Gain related to sale, including goodwill	$ 12,500,000
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	14	1
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		58
Aggregate proceeds		$ 193,700,000
Company's share of proceeds		193,100,000
Proceeds after debt assumptions and closing costs		133,800,000
Debt assumed		55,000,000
Gain related to sale, including goodwill		18,800,000
Goodwill included in sale		11,300,000
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
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
Gain related to sale of unconsolidated entities		10,200,000
Property Dispositions, 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified held for sale | property	7
Net gain (loss) on sale of properties	$ 0
Goodwill allocated to dispositions and held for sale assets	$ 0
2016 Property Dispositions [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on sale of properties		(1,700,000)
Goodwill allocated to dispositions and held for sale assets		$ 2,200,000