Earnings Per Share (Details) - 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	$ 2,537	$ 61,993	$ 43,564	$ 103,879
Convertible debt income adjustments, net of tax	0	443	0	1,047
Net income adjusted for convertible debt as used for diluted earnings per share	$ 2,537	$ 62,436	$ 43,564	$ 104,926
Net income per share:
Basic (in Dollars per share)	$ 0.02	$ 0.51	$ 0.35	$ 0.86
Diluted (in Dollars per share)	$ 0.02	$ 0.50	$ 0.35	$ 0.83
Shares used in computing net income per share:
Weighted average basic shares outstanding (in Shares)	124,660	121,374	124,541	120,401
Dilutive securities:
Stock option and unvested RSAs (in Shares)	534	1,365	314	1,474
Shares issuable upon conversion of convertible notes (in Shares)	0	3,185	0	4,059
Total dilutive securities (in Shares)	534	4,550	314	5,533
Weighted average diluted shares outstanding (in Shares)	125,194	125,924	124,855	125,934
Shares subject to stock options omitted from the calculation of income per share as their effect would have been anti-dilutive	2,268	2,430	3,991	2,740