Stock-based Compensation - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 0.8	$ 0.8	$ 2.6	$ 2.2
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period (in years)			4 years
Minimum | Restricted Stock | 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period (in years)			1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period (in years)			5 years
Maximum | Restricted Stock | 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period (in years)			4 years