Condensed Consolidated Statements of Changes in Equity Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total Equity	Non-controlling interest
Beginning balance (in shares) at Dec. 31, 2016		397,979,772		2,282,700
Beginning balance at Dec. 31, 2016	$ 975,770	$ 4,003	$ 1,226,206	$ (19,485)	$ (767)	$ (234,187)	$ 975,770	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation and related tax effects	62,078		63,475			(1,397)	62,078
Issuances under equity incentive plans, net of tax (in shares)		16,211,773
Issuances under equity incentive plans, net of tax	14,234	$ 162	14,072				14,234
ESPP purchase shares (in shares)		565,701
ESPP purchase shares	2,856	$ 5	2,851				2,856
Net unrealized gain on available for sale securities, net of tax	175				178		178	(3)
Contribution of interests in consolidated VIE	7,722						0	7,722
Dividends paid and return of capital to noncontrolling interests	(1,037)							(1,037)
Net loss	(61,828)					(61,828)	(61,828)	(119)
Net loss, including portion attributable to noncontrolling interest	(61,947)
Ending balance (in shares) at Sep. 30, 2017		414,757,246		2,282,700
Ending balance at Sep. 30, 2017	999,851	$ 4,170	1,306,604	$ (19,485)	(589)	(297,412)	993,288	6,563
Beginning balance (in shares) at Dec. 31, 2017		417,473,846		2,282,700
Beginning balance at Dec. 31, 2017	927,757	$ 4,198	1,327,206	$ (19,485)	(5)	(389,419)	922,495	5,262
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation and related tax effects	64,441		64,441			0	64,441
Issuances under equity incentive plans, net of tax (in shares)		7,740,443
Issuances under equity incentive plans, net of tax	(9,401)	$ 77	(9,478)				(9,401)
ESPP purchase shares (in shares)		937,607
ESPP purchase shares	2,773	$ 9	2,764				2,773
Net unrealized gain on available for sale securities, net of tax	235				177		177	58
Dividends paid and return of capital to noncontrolling interests	(2,972)						0	(2,972)
Net loss	(114,846)					(114,846)	(114,846)	105
Net loss, including portion attributable to noncontrolling interest	(114,741)
Ending balance (in shares) at Sep. 30, 2018		426,151,896		2,282,700
Ending balance at Sep. 30, 2018	$ 868,092	$ 4,284	$ 1,384,933	$ (19,485)	$ 172	$ (504,265)	$ 865,639	$ 2,453