Stock Plans and Other Incentives - Option Activity and Other Plan Data (Detail) - $ / shares	1 Months Ended	12 Months Ended
	May. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding at beginning of period, Options		582,500	627,724	645,448
Granted, Options	20,000	0	20,000	0
Exercised, Options		(35,000)	(56,362)	(8,862)
Cancelled through cash settlement, Options		0	(8,862)	(8,862)
Forfeited/cancelled/expired, Options		0	0	0
Outstanding at end of period, Options		547,500	582,500	627,724
Options exercisable at end of period, Options		531,500	562,500	627,724
Options exercisable which can be settled in cash, Options		0	0	17,724
Weighted average fair value of options granted per year (per option)	$ 7.64	$ 0.00	$ 7.64	$ 0.00
Weighted average remaining contractual life at end of period		3 years	3 years 10 months 24 days	4 years 6 months
Outstanding at beginning of period, Weighted-Average Exercise Price		$ 9.52	$ 9.05	$ 8.94
Granted, Weighted-Average Exercise Price	$ 18.52	0.00	18.52	0.00
Exercised, Weighted-Average Exercise Price		(8.12)	(8.25)	(5.24)
Cancelled through cash settlement, Weighted-Average Exercise Price		(0.00)	(4.09)	(5.24)
Forfeited/cancelled/expired, Weighted-Average Exercise Price		0	0	0
Outstanding at end of period, Weighted-Average Exercise Price		9.61	9.52	9.05
Options exercisable at end of period, Weighted-Average Exercise Price		9.35	9.21	9.05
Options exercisable which can be settled in cash, Weighted-Average Exercise Price		$ 0.00	$ 0.00	$ 4.09