Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income tax expense recognized in gain on sale of property, net of tax	$ 455	$ 853	$ 849	$ 1,987

This element represents the applicable amount of income taxes or benefit realized on the gain (loss) on sale of properties during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-15.(a)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

Name:	us-gaap_GainLossOnSaleOfPropertiesApplicableIncomeTaxes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration