Employee Benefit Plans - Schedule of Changes in Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Accumulated Other Comprehensive Income (Loss) Before Tax - Beginning Balance	$ 1,854	$ 5,032
Net actuarial gain (loss)	(3,523)	(1,760)	$ 17,566
Settlement gain	354	137	42
Actuarial (gains)/losses	1	0	2,037
Prior service costs/(credits)	(1,555)	(1,555)	(1,555)
Accumulated Other Comprehensive Income (Loss) Before Tax - Ending Balance	(2,869)	1,854	5,032
Income Tax Benefit (Expense) - Beginning Balance	(653)	(1,886)
Net actuarial gain (loss)	1,364	683	(6,811)
Settlement gain	(137)	(53)	(17)
Actuarial (gains)/losses	0	0	(790)
Prior service costs/(credits)	602	603
Income Tax Benefit (Expense) - Ending Balance	1,176	(653)	(1,886)
Accumulated Other Comprehensive Income (Loss) Net of Income Tax - Beginning Balance	1,201	3,146
Net actuarial gain (loss)	(2,159)	(1,077)	10,755
Settlement gain	217	84	25
Actuarial (gains)/losses	1	0	1,247
Prior service costs/(credits)	(953)	(952)	(951)
Accumulated Other Comprehensive Income (Loss) Net of Income Tax - Ending Balance	$ (1,693)	$ 1,201	$ 3,146