Stock-Based Employee Compensation Plans - Additional Information Regarding Vested and Unvested Options Outstanding (Details) - $ / shares	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding, exercise price, upper limit (in dollars per share)	$ 10.00
Options outstanding, vested (in shares)	576,670		529,284
Options outstanding, unvested (in shares)	500,682	215,926	479,817	468,504
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.45	$ 6.20	$ 6.12	$ 6.51
Options outstanding, weighted average remaining contractual life (years)	7 years 8 months 5 days
Options exercisable (in shares)	576,670		529,284
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.13		$ 5.80
$2.97 – $4.99
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding, exercise price, lower limit (in dollars per share)	2.97
Option outstanding, exercise price, upper limit (in dollars per share)	$ 4.99
Options outstanding, vested (in shares)	95,503
Options outstanding, unvested (in shares)	1,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 3.62
Options outstanding, weighted average remaining contractual life (years)	4 years 3 months 22 days
Options exercisable (in shares)	95,503
Options exercisable, weighted average exercise price (in dollars per share)	$ 3.61
$5.00 – $6.99
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding, exercise price, lower limit (in dollars per share)	5.00
Option outstanding, exercise price, upper limit (in dollars per share)	$ 6.99
Options outstanding, vested (in shares)	442,794
Options outstanding, unvested (in shares)	338,855
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.48
Options outstanding, weighted average remaining contractual life (years)	7 years 10 months 10 days
Options exercisable (in shares)	442,794
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.32
$7.00– $10.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding, exercise price, lower limit (in dollars per share)	$ 7
Options outstanding, vested (in shares)	24,573
Options outstanding, unvested (in shares)	160,827
Options outstanding, weighted average exercise price (in dollars per share)	$ 7.10
Options outstanding, weighted average remaining contractual life (years)	9 years 2 months 23 days
Options exercisable (in shares)	24,573
Options exercisable, weighted average exercise price (in dollars per share)	$ 7.10
$10.01-$17.31
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding, exercise price, lower limit (in dollars per share)	10.01
Option outstanding, exercise price, upper limit (in dollars per share)	$ 17.31
Options outstanding, vested (in shares)	13,800
Options outstanding, unvested (in shares)	0
Options outstanding, weighted average exercise price (in dollars per share)	$ 15.91
Options outstanding, weighted average remaining contractual life (years)	4 months 17 days
Options exercisable (in shares)	13,800
Options exercisable, weighted average exercise price (in dollars per share)	$ 15.91