Consolidated Statements of Comprehensive Loss Statement - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss attributable to Class A and Class B stockholders	$ (78,579)	$ (71,831)	$ (141,972)	$ (194,838)
Other comprehensive loss, net of taxes
Unrealized gain on available-for-sale securities	1	12	25	12
Change in effective portion of interest rate swap	1,240	60	5,156	(243)
Other comprehensive income (loss)	1,241	72	5,181	(231)
Comprehensive loss	(77,338)	(71,759)	(136,791)	(195,069)
Comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interests	(1,182)	3	(4,745)	384
Comprehensive loss attributable to Class A and Class B stockholders	$ (78,520)	$ (71,756)	$ (141,536)	$ (194,685)