Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 61,993	$ 32,508	$ 103,879	$ 70,046
Convertible debt income adjustments, net of tax	443	927	1,047	2,034
Net income adjusted for convertible debt as used for diluted earnings per share	$ 62,436	$ 33,435	$ 104,926	$ 72,080
Net income per share:
Basic (in Dollars per share)	$ 0.51	$ 0.28	$ 0.86	$ 0.61
Diluted (in Dollars per share)	$ 0.50	$ 0.27	$ 0.83	$ 0.57
Shares used in computing net income per share:
Weighted average basic shares outstanding (in Shares)	121,374	115,808	120,401	114,587
Dilutive securities:
Stock option and unvested RSAs (in Shares)	1,365	1,655	1,474	1,869
Shares issuable upon conversion of convertible notes (in Shares)	3,185	8,456	4,059	9,194
Total dilutive securities (in Shares)	4,550	10,111	5,533	11,063
Weighted average diluted shares outstanding (in Shares)	125,924	125,919	125,934	125,650
Shares subject to stock options omitted from the calculation of income per share as their effect would have been anti-dilutive (in Shares)	2,430	874	2,740	724