Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Statement Of Stockholders Equity [Abstract]
Net loss allocated to redeemable non-controlling interest	$ 277	$ 347
Distributions declared on common stock per share	$ 0.1582	$ 0.1552

Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.19)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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