Consolidated Statements of Comprehensive Loss Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss attributable to Class A and Class B stockholders	$ (241,753)	$ (262,599)	$ (279,658)
Other comprehensive income (loss), net of taxes:
Unrealized gain (loss) on available-for-sale securities	26	(13)	0
Change in effective portion of interest rate swap	2,098	894	(418)
Other comprehensive income (loss)	2,124	881	(418)
Comprehensive loss	(239,629)	(261,718)	(280,076)
Comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interests	(1,831)	(501)	720
Comprehensive loss attributable to Class A and Class B stockholders	$ (241,460)	$ (262,219)	$ (279,356)