Equity Investments in Real Estate - Proportionate Share of Income (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	$ 4,683	$ 1,985
Equity Method Investments
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	5,295	2,847
Equity Method Investments \| Net Lease
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	4,702	4,955
Equity Method Investments \| All Other
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	593	(2,108)
Amortization of Basis Difference on Equity Investments
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(612)	(862)
Amortization of Basis Difference on Equity Investments \| Net Lease
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(535)	(563)
Amortization of Basis Difference on Equity Investments \| All Other
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	$ (77)	$ (299)

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(f))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration