Stockholders' Equity (Summary of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Options
Outstanding Options, Beginning of period			12,240,467
Options granted			2,395,789
Options exercised			(1,262,020)
Options cancelled			(174,783)
Options expired			(245,538)
Outstanding Options, End of period	12,953,915		12,953,915
Exercisable at the end of period	8,183,715		8,183,715
Weighted-Average Exercise Price
Outstanding Exercise Price (in dollars per share)			$ 15.41
Options granted (in dollars per share)			12.19
Options exercised (in dollars per share)			13.93
Options cancelled (in dollars per share)			13.48
Options expired (in dollars per share)			23.84
Outstanding Exercise Price (in dollars per share)	$ 14.82		14.82
Exercisable at the end of period	$ 15.59		$ 15.59
Additional Disclosures
Outstanding Contractual Term (in Years)			4 years 6 months
Outstanding Intrinsic Value	$ 67,739		$ 67,739
Exercisable at the end of period (in Years)			2 years 11 months 27 days
Exercisable aggregate intrinsic value	41,704		$ 41,704
Allocated share base compensation	3,555	$ 3,427	11,604	$ 9,357
Employee Stock Option
Additional Disclosures
Allocated share base compensation	$ 1,900	$ 2,100	$ 6,700	$ 6,100