Equity Investments in the Managed Programs and Real Estate - Summary of Earnings from Equity Method Investments in the Managed Programs and Real Estate (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Schedule Of Equity Method Investments
Distributions of Available Cash (Note 3)	$ 15,325	$ 15,774
Proportionate share of equity in earnings of equity investments in the Managed Programs	15,325	15,774
Managed Programs
Schedule Of Equity Method Investments
Distributions of Available Cash (Note 3)	10,502	11,793
Proportionate share of equity in earnings of equity investments in the Managed Programs	1,863	2,199
Amortization of basis differences on equity investments	(398)	(290)
Total equity in earnings of equity method investments in the Managed Programs	11,967	13,702
Jointly Owned Investments
Schedule Of Equity Method Investments
Proportionate share of equity in earnings of equity investments in the Managed Programs	3,903	2,944
Amortization of basis differences on equity investments	(545)	(872)
Investment in real estate
Schedule Of Equity Method Investments
Proportionate share of equity in earnings of equity investments in the Managed Programs	$ 3,358	$ 2,072

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
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-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

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