Consolidated Statements of Comprehensive Loss Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss attributable to common stockholders	$ (45,677)	$ (63,475)	$ (63,393)	$ (123,007)
Other comprehensive gain (loss), net of taxes
Unrealized gain on available-for-sale securities	100	0	91	0
Change in effective portion of interest rate swap	986	(923)	3,853	(304)
Other comprehensive gain (loss)	1,086	(923)	3,944	(304)
Comprehensive loss	(44,591)	(64,398)	(59,449)	(123,311)
Comprehensive income (loss) attributable to noncontrolling interests and redeemable noncontrolling interests	(984)	882	(3,563)	381
Comprehensive loss attributable to common stockholders	$ (45,575)	$ (63,516)	$ (63,012)	$ (122,930)