Consolidated Statements of Changes in Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Net loss attributable to redeemable noncontrolling interest	$ (1,327)	$ (6,051)
Payments to acquire noncontrolling interest		$ 10,800