Employee Benefits and Incentive Plans - 2006 Executive Incentive Plan and 2013 Long-Term Incentive Plan - Stock Options - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Companies shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options granted and outstanding, expected to vest | shares	2,238,685
Intrinsic value of options exercisable	$ 0.6
Aggregate intrinsic value of options outstanding	0.6
Aggregate intrinsic value of options outstanding, vested and expected to vest	$ 0.6
Share based compensation historical volatility period	5 years
Number of companies in peer group | Companies	12
Number of Options, Granted | shares	0