Stockholders' Equity (Summary of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Options
Outstanding Options, Beginning of period			12,240,467
Options granted			2,382,036
Options exercised			(280,303)
Options cancelled			(126,225)
Options expired			(233,136)
Outstanding Options, End of period	13,982,839		13,982,839
Exercisable at the end of period	8,039,685		8,039,685
Weighted-Average Exercise Price
Outstanding Exercise Price (in dollars per share)			$ 15.41
Options granted (in dollars per share)			12.15
Options exercised (in dollars per share)			11.61
Options cancelled (in dollars per share)			13.46
Options expired (in dollars per share)			24.11
Outstanding Exercise Price (in dollars per share)	$ 14.80		14.80
Exercisable at the end of period	$ 16.02		$ 16.02
Additional Disclosures
Outstanding Contractual Term (in Years)			4 years 7 months 13 days
Outstanding Intrinsic Value	$ 37,001		$ 37,001
Exercisable at the end of period (in Years)			3 years 3 months
Exercisable aggregate intrinsic value	19,081		$ 19,081
Allocated share base compensation	4,198	$ 3,700	8,049	$ 5,930
Employee Stock Option
Additional Disclosures
Allocated share base compensation	$ 2,500	$ 2,400	$ 4,800	$ 4,000