Net Income per Share - Schedule of Components Used in Diluted and Basic Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator [Abstract]
Net income (in dollars)	$ 76,000	$ 88,040	$ 224,493	$ 232,986
Denominator [Abstract]
Shares used for basic net income per share	174,429	178,547	175,444	178,591
Effect of dilutive securities:
Convertible senior notes (in shares)	0	0	0	0
Warrants related to issuance of convertible senior notes (in shares)	0	0	0	0
Shares used for diluted net income per share	175,617	180,364	176,525	180,642
Basic net income per share (in dollars per share)	$ 0.44	$ 0.49	$ 1.28	$ 1.30
Diluted net income per share (in dollars per share)	$ 0.43	$ 0.49	$ 1.27	$ 1.29
Stock options
Effect of dilutive securities:
Dilutive securities (in shares)	341	667	380	858
RSUs and deferred stock units
Effect of dilutive securities:
Dilutive securities (in shares)	847	1,150	701	1,193