Basic and Diluted Net (Loss) Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net (loss) income		$ (35,363)	$ 84,090
Weighted-average number of shares of common stock and common stock equivalents outstanding:
Weighted-average number of shares of common stock outstanding for computing basic (loss) earnings per share		64,631	54,850
Dilutive effect of outstanding stock awards and stock options after application of the treasury stock method	[1]	0	1,162
Weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for computing diluted loss per share		64,631	56,012
Net (loss) earnings per share - basic and diluted
Basic (loss) earnings per share		$ (0.55)	$ 1.53
Diluted (loss) earnings per share		$ (0.55)	$ 1.50

[1] For the three months ended March 31, 2018, stock options, RSAs, RSUs, stock appreciation rights and potentially issuable stock for ESPP to purchase 9.9 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive.  For the three months ended March 31, 2017, out of money stock options, unvested performance-based RSUs and RSAs whose performance milestones were not achieved and potentially issuable stock for ESPP to purchase approximately 3.4 million were excluded from the net earnings per share calculation as their effect would have been anti-dilutive.