CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (unaudited) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Statement of Cash Flows [Abstract]
Interest capitalized	$ 2,452	$ 1,543

Amount of interest capitalized during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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