Condensed Consolidated Statements of Convertible Redeemable Preferred Stock, Redeemable Noncontrolling Interest, Stockholders' Deficit and Noncontrolling Interest (unaudited) - USD ($) $ in Thousands		Total	Stockholders' Deficit	Common Stock		Additional Paid-In Capital	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit	Redeemable Noncontrolling Interest	Noncontrolling Interest	Convertible Redeemable Preferred Stock
Beginning balance (in shares) at Dec. 31, 2017	[1]			10,353,269
Beginning balance at Dec. 31, 2017			$ (2,180,005)	$ 1	[1]	$ 150,803	$ (162)	$ (2,330,647)
Beginning balance at Dec. 31, 2017									$ 58,154	$ 155,372
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Revaluation of common stock warrants			(66)			(66)
Issuance of restricted stock awards (in shares)	[1]			3,615
Issuance of restricted stock awards			67			67
Exercise of stock options (in shares)	[1]			213,757
Exercise of stock options			743			743
Stock-based compensation expense			15,256			15,256
Unrealized gain on available for sale securities		$ 91	91				91
Change in effective portion of interest rate swap agreement		3,853	288				288		2	3,563
Distributions to noncontrolling interests									(6,213)	(5,362)
Net income (loss)		(72,536)	(63,393)					(63,393)	2,997	(12,140)
Ending balance (in shares) at Jun. 30, 2018	[1]			10,570,641
Ending balance at Jun. 30, 2018			(2,227,019)	$ 1	[1]	166,803	217	(2,394,040)
Ending balance at Jun. 30, 2018									54,940	141,433
Beginning balance (in shares) at Dec. 31, 2017											71,740,162
Beginning balance at Dec. 31, 2017											$ 1,465,841
Ending balance (in shares) at Jun. 30, 2018											71,740,162
Ending balance at Jun. 30, 2018											$ 1,465,841
Beginning balance (in shares) at Mar. 31, 2018	[1]			10,424,982
Beginning balance at Mar. 31, 2018			(2,189,641)	$ 1	[1]	158,604	117	(2,348,363)
Beginning balance at Mar. 31, 2018									58,176	149,759
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Revaluation of common stock warrants			(66)			(66)
Exercise of stock options (in shares)	[1]			145,659
Exercise of stock options			623			623
Stock-based compensation expense			7,642			7,642
Unrealized gain on available for sale securities		100	100				100
Change in effective portion of interest rate swap agreement		986							(1)	987
Distributions to noncontrolling interests									(4,741)	(3,296)
Net income (loss)		(50,188)	(45,677)					(45,677)	1,506	(6,017)
Ending balance (in shares) at Jun. 30, 2018	[1]			10,570,641
Ending balance at Jun. 30, 2018			(2,227,019)	$ 1	[1]	166,803	217	(2,394,040)
Ending balance at Jun. 30, 2018									54,940	141,433
Beginning balance (in shares) at Mar. 31, 2018											71,740,162
Beginning balance at Mar. 31, 2018											$ 1,465,841
Ending balance (in shares) at Jun. 30, 2018											71,740,162
Ending balance at Jun. 30, 2018											$ 1,465,841
Beginning balance (in shares) at Dec. 31, 2018				109,421,183
Beginning balance at Dec. 31, 2018		(91,661)	(91,661)	$ 11		2,480,597	131	(2,572,400)
Beginning balance at Dec. 31, 2018									57,261	125,110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards (in shares)				3,504,098
ESPP purchase (in shares)				696,036
ESPP purchase			6,916			6,916
Exercise of stock options (in shares)				328,026
Exercise of stock options			1,405			1,405
Stock-based compensation expense			114,361			114,361
Unrealized gain on available for sale securities		26	26				26
Change in effective and ineffective portion of interest rate swap agreement			(305)				(305)			(5,388)
Change in effective portion of interest rate swap agreement		(5,693)
Distributions to noncontrolling interests									(3,537)	(4,208)
Mandatory redemption of noncontrolling interests									(55,684)
Net income (loss)		(155,504)	(146,657)					(146,657)	2,465	(11,312)
Ending balance (in shares) at Jun. 30, 2019				113,949,343
Ending balance at Jun. 30, 2019		(115,785)	(115,785)	$ 11		2,603,279	(148)	(2,718,927)
Ending balance at Jun. 30, 2019									505	104,072
Beginning balance (in shares) at Dec. 31, 2018											0
Beginning balance at Dec. 31, 2018											$ 0
Ending balance (in shares) at Jun. 30, 2019											0
Ending balance at Jun. 30, 2019											$ 0
Beginning balance (in shares) at Mar. 31, 2019				113,214,063
Beginning balance at Mar. 31, 2019			(105,439)	$ 11		2,551,256	5	(2,656,711)
Beginning balance at Mar. 31, 2019									58,802	114,664
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards (in shares)				543,636
Exercise of stock options (in shares)				191,644
Exercise of stock options			828			828
Stock-based compensation expense			51,195			51,195
Unrealized gain on available for sale securities		9	9				9
Change in effective and ineffective portion of interest rate swap agreement			(162)				(162)			(3,340)
Change in effective portion of interest rate swap agreement		(3,502)
Distributions to noncontrolling interests									(3,255)	(1,595)
Mandatory redemption of noncontrolling interests									(55,684)
Net income (loss)		(67,231)	(62,216)					(62,216)	642	(5,657)
Ending balance (in shares) at Jun. 30, 2019				113,949,343
Ending balance at Jun. 30, 2019		$ (115,785)	$ (115,785)	$ 11		$ 2,603,279	$ (148)	$ (2,718,927)
Ending balance at Jun. 30, 2019									$ 505	$ 104,072
Beginning balance (in shares) at Mar. 31, 2019											0
Beginning balance at Mar. 31, 2019											$ 0
Ending balance (in shares) at Jun. 30, 2019											0
Ending balance at Jun. 30, 2019											$ 0

[1] Common Stock issued and converted to Class A Common and Class B Common effective July 2018.