Fair Value Measurements - Carrying Value and Fair Value Measurements (Details) - Level 3 - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Carrying Value
Liabilities
Debt, net	$ 1,368,436	$ 1,275,448
Notes receivable	63,954	66,500
Fair Value
Liabilities
Debt, net	1,389,201	1,301,844
Notes receivable	$ 66,454	$ 69,000

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant