Stockholders' Equity (Schedule of Share-based Compensation Arrangements by Share-based Payment Award) (Details) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended
	Jun. 30, 2015	May. 31, 2015 program	Feb. 28, 2011	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 $ / shares shares	Dec. 31, 2013 $ / shares shares	Jul. 07, 2015 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Intrinsic value, exercises in period | $				$ 6.0
Weighted average grant date fair value, vested | $				$ 3.5
Weighted average remaining contractual term, vested and exercisable				5 years 4 months 2 days
Weighted average remaining contractual term, outstanding				4 years 9 months 22 days
Restricted stock award activity
Share price (in dollars per share) | $ / shares							$ 15.00
Stock options
Number of Options
Balance outstanding at the beginning of the period (in shares)				5,355,567	4,869,330	4,775,979
Granted (in shares)				403,086	1,037,547	869,540
Exercised (in shares)				(383,458)	(118,738)	(258,909)
Expired (in shares)				(30,876)	(142,206)	(276,349)
Cancelled/Forfeited (in shares)				(95,990)	(290,366)	(240,931)
Balance outstanding at the end of the period (in shares)				5,248,329	5,355,567	4,869,330
Total vested and exercisable (in shares)				4,344,937
Weighted Average Exercise Price per Share
Balance at the beginning of the period (in dollars per share) | $ / shares				$ 4.87	$ 3.77	$ 3.44
Granted (in dollars per shares) | $ / shares				12.20	9.77	5.50
Exercised (in dollars per share) | $ / shares				2.10	1.50	2.01
Expired (in dollars per share) | $ / shares				5.97	5.29	4.00
Cancelled/Forfeited (in dollars per share) | $ / shares				7.42	5.08	5.14
Balance at the end of the period (in dollars per share) | $ / shares				2.44	$ 4.87	$ 3.77
Total vested and exercisable | $ / shares				$ 4.66
2004 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Expiration period			10 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity programs | program		2
2011 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Expiration period	10 years
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance, before transfers and annual increases (in shares)				2,000,000
Maximum annual increase in common stock available for issuance (in shares)				3,000,000
Maximum annual increase in common stock available for issuance (as a percent)				3.00%
Common stock available for future issuance (in shares)				2,336,491
2015 Plan | Restricted stock awards
Restricted stock award activity
Awards granted (in shares)				174,530
Share price (in dollars per share) | $ / shares				$ 22.31
Vested (in shares)				0