Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Class A,B, and C Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance, Value at Dec. 31, 2014	$ 1,895,692	$ 5	$ 3,096,977		$ (29,175)	$ (1,172,115)
Beginning balance, Shares at Dec. 31, 2014		905,860,000
Exercise of stock options and ESPP	7,567		7,567
Exercise of stock options and ESPP, Shares		7,075,000
Vesting of ZSUs, net of tax withholdings	(2,901)	$ 1	(2,130)	$ (772)
Vesting of ZSUs, net of tax withholdings		27,966,000
Contributed capital, related to common control acquisition	(109)		1,854			(1,963)
Stock-based compensation expense	129,591		129,591
Stock-based compensation expense, Shares		717,000
Vesting of common stock following the early exercise of options	170		170
Repurchases of common stock	(98,902)			(98,902)
Repurchases of common stock, Shares		(38,001,000)
Retirements of treasury stock				732		(732)
Tax cost (benefit) from stock-based expense	516		516
Net income (loss)	(121,510)					(121,510)
Other comprehensive income (loss)	(23,213)				(23,213)
Ending balance, Value at Dec. 31, 2015	1,786,901	$ 6	3,234,545	(98,942)	(52,388)	(1,296,320)
Ending balance, Shares at Dec. 31, 2015		903,617,000
Exercise of stock options and ESPP	5,921		5,921
Exercise of stock options and ESPP, Shares		6,989,000
Vesting of ZSUs, net of tax withholdings	(3,423)		(2,582)	(841)
Vesting of ZSUs, net of tax withholdings		30,794,000
Stock-based compensation expense	111,824		111,824
Repurchases of common stock	(136,080)			(136,080)
Repurchases of common stock, Shares		(54,550,000)
Retirements of treasury stock				235,863		(235,863)
Net income (loss)	(108,173)					(108,173)
Other comprehensive income (loss)	(76,306)				(76,306)
Ending balance, Value at Dec. 31, 2016	1,580,664	$ 6	3,349,708		(128,694)	(1,640,356)
Ending balance, Shares at Dec. 31, 2016		886,850,000
Exercise of stock options and ESPP	8,769		8,769
Exercise of stock options and ESPP, Shares		5,365,000
Vesting of ZSUs, net of tax withholdings	(21,719)		(427)	(21,292)
Vesting of ZSUs, net of tax withholdings		14,768,000
Stock-based compensation expense	64,515		64,515
Repurchases of common stock	(101,036)	$ (1)		(101,035)
Repurchases of common stock, Shares		(36,323,000)
Retirements of treasury stock				$ 122,327		(122,327)
Adoption of ASU 2016-09	48,211		3,935			44,276
Net income (loss)	26,639					26,639
Other comprehensive income (loss)	35,197				35,197
Ending balance, Value at Dec. 31, 2017	$ 1,641,240	$ 5	$ 3,426,500		$ (93,497)	$ (1,691,768)
Ending balance, Shares at Dec. 31, 2017		870,660,000