Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income from continuing operations	$ 45,805	$ 39,302	$ 87,867	$ 1,975
Net income from discontinued operations	0	5,409	0	11,625
Net income	$ 45,805	$ 44,711	$ 87,867	$ 13,600
Weighted-average shares used to calculate basic EPS	77,923	69,729	75,383	68,931
Effect of dilutive securities:
Employee equity awards	585	635	625	644
Weighted-average shares used to calculate diluted EPS	78,508	70,364	76,008	69,575
Basic EPS:
Basic EPS from continuing operations (in dollars per share)	$ 0.59	$ 0.56	$ 1.17	$ 0.03
Basic EPS from discontinued operations (in dollars per share)	0.00	0.08	0.00	0.17
Basic EPS (in dollars per share)	0.59	0.64	1.17	0.20
Diluted EPS:
Diluted EPS from continuing operations (in dollars per share)	0.58	0.56	1.16	0.03
Diluted EPS from discontinued operations (in dollars per share)	0.00	0.08	0.00	0.17
Diluted EPS (in dollars per share)	$ 0.58	$ 0.64	$ 1.16	$ 0.20