CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Increase (Decrease) in Stockholders' Equity
Adoption of ASU | ASU 2016-01			$ (2,753)	$ 2,753
Balances at Dec. 31, 2017	$ 211	$ 3,627,433	(7,010)	(1,990,005)	$ 1,630,629
Increase (Decrease) in Stockholders' Equity
Issuance of shares of Common Stock upon exercise of stock options and settlement of employee restricted stock units	1	2,575			2,576
Issuance of shares of Common Stock for services rendered		87			87
Issuance of shares of Common Stock upon conversion of Convertible Senior Notes		27			27
Stock compensation		36,224			36,224
Other comprehensive income (loss)			(359)		(359)
Net income (loss)				(41,140)	(41,140)
Balances at Mar. 31, 2018	212	3,666,346	(10,122)	(2,028,392)	1,628,044
Increase (Decrease) in Stockholders' Equity
Adoption of ASU | ASU No. 2016-02				95	95
Balances at Dec. 31, 2018	213	3,813,678	(10,165)	(1,877,759)	1,925,967	[1]
Increase (Decrease) in Stockholders' Equity
Issuance of shares of Common Stock upon exercise of stock options and settlement of employee restricted stock units	1	15,480			15,481
Issuance of shares of Common Stock for services rendered		104			104
Stock compensation		40,690			40,690
Other comprehensive income (loss)			918		918
Net income (loss)				102,312	102,312
Balances at Mar. 31, 2019	$ 214	$ 3,869,952	$ (9,247)	$ (1,775,352)	$ 2,085,567

[1] The condensed consolidated balance sheet at December 31, 2018 has been derived from the audited financial statements at that date.