CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Common Stock	Additional Paid-in Capital	Company Stock Held By NQDC	Accumulated other comprehensive income (loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017	[1]			175,844,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				2,059,000
Ending balance (in shares) at Sep. 30, 2018				177,903,000
Beginning Balance at Dec. 31, 2017	[1]	$ 2,808,663		$ 176	$ 4,483,220	$ (14,224)	$ (22,961)	$ (1,637,548)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				2	21,461
Stock-based compensation					116,136
Common stock held by the NQDC						809
Accounting impact of NQDC Plan change					0	0
Other comprehensive income (loss)							21,387
Net income (loss)		(73,561)						(73,561)
Ending Balance at Sep. 30, 2018		2,914,945		$ 178	4,620,817	(13,415)	(2,160)	(1,690,475)
Beginning balance (in shares) at Jun. 30, 2018	[1]			177,508,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				395,000
Ending balance (in shares) at Sep. 30, 2018				177,903,000
Beginning Balance at Jun. 30, 2018	[1]	2,885,104		$ 178	4,577,300	(13,390)	(1,129)	(1,677,855)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				0	5,151
Stock-based compensation					38,366
Common stock held by the NQDC					0	(25)
Accounting impact of NQDC Plan change					0	0
Other comprehensive income (loss)							(1,031)
Net income (loss)		(12,620)						(12,620)
Ending Balance at Sep. 30, 2018		2,914,945		$ 178	4,620,817	(13,415)	(2,160)	(1,690,475)
Beginning balance (in shares) at Dec. 31, 2018	[1]			178,253,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				1,351,000
Ending balance (in shares) at Sep. 30, 2019				179,604,000
Beginning Balance at Dec. 31, 2018	[1]	2,967,940	[2]	$ 178	4,669,926	(13,301)	5,271	(1,694,134)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				2	(19,183)
Stock-based compensation					122,212
Common stock held by the NQDC					(692)	692
Accounting impact of NQDC Plan change					10,653	2,648
Other comprehensive income (loss)							31,732
Net income (loss)		(38,872)						(38,872)
Ending Balance at Sep. 30, 2019		3,074,405		$ 180	4,782,916	(9,961)	37,003	(1,735,733)
Beginning balance (in shares) at Jun. 30, 2019	[1]			179,433,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				171,000
Ending balance (in shares) at Sep. 30, 2019				179,604,000
Beginning Balance at Jun. 30, 2019	[1]	2,960,954		$ 179	4,744,316	(10,211)	17,439	(1,790,769)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				1	(1,294)
Stock-based compensation					40,144
Common stock held by the NQDC					(250)	250
Accounting impact of NQDC Plan change					0	0
Other comprehensive income (loss)							19,564
Net income (loss)		55,036						55,036
Ending Balance at Sep. 30, 2019		$ 3,074,405		$ 180	$ 4,782,916	$ (9,961)	$ 37,003	$ (1,735,733)

[1] The beginning balances for the nine-month periods were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the SEC on February 28, 2019.

[2] December 31, 2018 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the SEC on February 28, 2019.