Stock-based Compensation (Stock Option Exercise Price Range) (Details) (Employee Stock Option [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options (options)	3,481
Weighted Average Remaining Contractual Term (years)	6 years 6 months 15 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share)	$ 4.53
Number of Options Exercisable (number of options)	2,072
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share)	$ 6.04
$0.90 - $1.97 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options (options)	889
Weighted Average Remaining Contractual Term (years)	8 years 1 month 28 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share)	$ 1.83
Number of Options Exercisable (number of options)	113
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share)	$ 1.05
Exercise price range, lower range limit (dollars per share)	$ 0.90
Exercise price range, upper range limit (dollars per share)	$ 1.97
$1.98 - $2.45 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options (options)	920
Weighted Average Remaining Contractual Term (years)	6 years 5 months 16 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share)	$ 2.35
Number of Options Exercisable (number of options)	491
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share)	$ 2.38
Exercise price range, lower range limit (dollars per share)	$ 1.98
Exercise price range, upper range limit (dollars per share)	$ 2.45
$3.41 - $7.46 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options (options)	916
Weighted Average Remaining Contractual Term (years)	6 years 2 months 27 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share)	$ 4.67
Number of Options Exercisable (number of options)	719
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share)	$ 4.98
Exercise price range, lower range limit (dollars per share)	$ 3.41
Exercise price range, upper range limit (dollars per share)	$ 7.46
$7.81 - $11.87 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options (options)	756
Weighted Average Remaining Contractual Term (years)	5 years 1 month 13 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share)	$ 10.21
Number of Options Exercisable (number of options)	749
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share)	$ 10.22
Exercise price range, lower range limit (dollars per share)	$ 7.81
Exercise price range, upper range limit (dollars per share)	$ 11.87