Consolidated Statements of Cashflows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Cash Flows [Abstract]
Cash and cash equivalents	$ 21,268	$ 74,823	$ 71,805
Restricted cash	13,580	10,846	22,904
Cash paid for capitalized interest	$ 5,625	$ 13,509	$ 21,109