Stock-Based Compensation Plans - Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock options outstanding	2,641,592
Options exercisable	2,127,288
$0.55-4.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 0.55
Exercise price, upper limit (in dollars per share) | $ / shares	$ 4.60
Stock options outstanding	278,755
Weighted-average remaining contractual life	6 years 7 months 6 days
Options exercisable	185,111
4.62-4.62 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 4.62
Exercise price, upper limit (in dollars per share) | $ / shares	$ 4.62
Stock options outstanding	90,000
Weighted-average remaining contractual life	6 years 10 months 24 days
Options exercisable	55,625
5.04-5.04 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 5.04
Exercise price, upper limit (in dollars per share) | $ / shares	$ 5.04
Stock options outstanding	1,431,092
Weighted-average remaining contractual life	6 years 7 months 6 days
Options exercisable	1,252,213
5.06-6.34 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 5.06
Exercise price, upper limit (in dollars per share) | $ / shares	$ 6.34
Stock options outstanding	295,572
Weighted-average remaining contractual life	6 years 10 months 24 days
Options exercisable	242,576
6.38-10.20 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 6.38
Exercise price, upper limit (in dollars per share) | $ / shares	$ 10.20
Stock options outstanding	287,135
Weighted-average remaining contractual life	6 years 6 months
Options exercisable	240,224
11.30-17.44 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 11.30
Exercise price, upper limit (in dollars per share) | $ / shares	$ 17.44
Stock options outstanding	56,229
Weighted-average remaining contractual life	7 years 4 months 24 days
Options exercisable	32,267
17.48-17.48 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 17.48
Exercise price, upper limit (in dollars per share) | $ / shares	$ 17.48
Stock options outstanding	90,000
Weighted-average remaining contractual life	8 years 4 months 24 days
Options exercisable	90,000
20.88-20.88 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 20.88
Exercise price, upper limit (in dollars per share) | $ / shares	$ 20.88
Stock options outstanding	47,187
Weighted-average remaining contractual life	8 years 1 month 6 days
Options exercisable	20,105
21.00-21.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 21.00
Exercise price, upper limit (in dollars per share) | $ / shares	$ 21.00
Stock options outstanding	20,000
Weighted-average remaining contractual life	8 years 2 months 12 days
Options exercisable	9,167
$34.65-34.65 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share) | $ / shares	$ 34.65
Exercise price, upper limit (in dollars per share) | $ / shares	$ 34.65
Stock options outstanding	45,622
Weighted-average remaining contractual life	9 years 1 month 6 days
Options exercisable	0