Stockholders' Equity (Summary of Options by Range of Exercise Prices) (Details)	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Number of shares outstanding | shares	8,366,000
Options outstanding, Weighted-average remaining contractual life	6 years 1 month 10 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 10.99
Options exercisable, Number of shares | shares	5,754,000
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 10.96
$1.79 - $7.02 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	1.79
Exercise price range, maximum (in dollars per share)	$ 7.02
Options outstanding, Number of shares outstanding | shares	1,149,899
Options outstanding, Weighted-average remaining contractual life	2 years 6 months 8 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 5.04
Options exercisable, Number of shares | shares	1,134,899
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 5.03
$7.04 - $9.24 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	7.04
Exercise price range, maximum (in dollars per share)	$ 9.24
Options outstanding, Number of shares outstanding | shares	1,044,654
Options outstanding, Weighted-average remaining contractual life	6 years 11 months 1 day
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 8.73
Options exercisable, Number of shares | shares	556,154
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 8.88
$9.34 - $10.05 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	9.34
Exercise price range, maximum (in dollars per share)	$ 10.05
Options outstanding, Number of shares outstanding | shares	977,025
Options outstanding, Weighted-average remaining contractual life	7 years 9 months 22 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 9.77
Options exercisable, Number of shares | shares	463,700
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 9.72
$10.09 - $10.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	10.09
Exercise price range, maximum (in dollars per share)	$ 10.09
Options outstanding, Number of shares outstanding | shares	3,500
Options outstanding, Weighted-average remaining contractual life	4 years 7 months 20 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 10.09
Options exercisable, Number of shares | shares	3,500
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 10.09
$10.13 - $10.13 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	10.13
Exercise price range, maximum (in dollars per share)	$ 10.13
Options outstanding, Number of shares outstanding | shares	1,219,400
Options outstanding, Weighted-average remaining contractual life	7 years 8 months 7 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 10.13
Options exercisable, Number of shares | shares	616,400
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 10.13
$10.31 - $12.32 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	10.31
Exercise price range, maximum (in dollars per share)	$ 12.32
Options outstanding, Number of shares outstanding | shares	945,000
Options outstanding, Weighted-average remaining contractual life	6 years 2 months 20 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 11.21
Options exercisable, Number of shares | shares	693,525
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 11.47
$12.46 - $13.28 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	12.46
Exercise price range, maximum (in dollars per share)	$ 13.28
Options outstanding, Number of shares outstanding | shares	1,295,150
Options outstanding, Weighted-average remaining contractual life	5 years 2 months 3 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 13.09
Options exercisable, Number of shares | shares	1,141,650
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 13.09
$13.34 - $16.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	13.34
Exercise price range, maximum (in dollars per share)	$ 16.00
Options outstanding, Number of shares outstanding | shares	840,100
Options outstanding, Weighted-average remaining contractual life	7 years 1 month 5 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 14.23
Options exercisable, Number of shares | shares	454,863
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 14.71
$16.98 - $18.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	16.98
Exercise price range, maximum (in dollars per share)	$ 18.09
Options outstanding, Number of shares outstanding | shares	886,425
Options outstanding, Weighted-average remaining contractual life	6 years
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 17.45
Options exercisable, Number of shares | shares	684,225
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 17.46
$18.24 - $18.24 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	18.24
Exercise price range, maximum (in dollars per share)	$ 18.24
Options outstanding, Number of shares outstanding | shares	5,000
Options outstanding, Weighted-average remaining contractual life	6 years 1 month
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 18.24
Options exercisable, Number of shares | shares	3,750
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 18.24