Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net income from continuing operations	$ 79,900	$ 48,769	$ 167,767	$ 50,744
Net income from discontinued operations	0	2,681	0	14,306
Net income	$ 79,900	$ 51,450	$ 167,767	$ 65,050
Weighted-average shares used to calculate basic EPS	78,055	71,190	76,283	69,689
Effect of dilutive securities:
Employee equity awards	664	718	665	700
Weighted-average shares used to calculate diluted EPS	78,719	71,908	76,948	70,389
Basic EPS:
Basic EPS from continuing operations (in dollars per share)	$ 1.02	$ 0.69	$ 2.20	$ 0.73
Basic EPS from discontinued operations (in dollars per share)	0.00	0.04	0.00	0.21
Basic EPS (in dollars per share)	1.02	0.73	2.20	0.94
Diluted EPS:
Diluted EPS from continuing operations (in dollars per share)	1.02	0.68	2.18	0.72
Diluted EPS from discontinued operations (in dollars per share)	0.00	0.04	0.00	0.20
Diluted EPS (in dollars per share)	$ 1.02	$ 0.72	$ 2.18	$ 0.92