Employee Benefit Plans - Summary of Defined Benefit Plans Combined Activity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit obligation, Beginning Balance	$ 46,400
Benefit obligation, Interest cost	1,661	$ 1,754	$ 1,740
Benefit obligation, Actuarial loss (gain)	(2,123)	(1,316)	(2,318)
Defined Benefit Plan, Benefit obligation, Ending Balance	41,500	46,400
Accrued benefit liability	(8,337)	(8,753)
Net amount recognized	(8,337)	(8,753)
Net actuarial loss	11,860	14,863
Amount Recognized in OCI, Total	11,860	14,863
Change in Projected Benefit Obligation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit obligation, Beginning Balance	46,446	41,321
Benefit obligation, Interest cost	1,661	1,754
Plan Assets, Benefits paid	(869)	(931)
Benefit obligation, Actuarial loss (gain)	(1,916)	6,287
Plan Assets, Settlement	(3,773)	(1,985)
Defined Benefit Plan, Benefit obligation, Ending Balance	41,549	46,446	41,321
Change in Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair value of plan assets, Beginning Balance	37,693	37,916
Plan Assets, Actual return on plan assets	(39)	2,260
Plan Assets, Employer contributions	200	433
Plan Assets, Benefits paid	(869)	(931)
Plan Assets, Settlement	(3,773)	(1,985)
Defined Benefit Plan, Fair value of plan assets, Ending Balance	33,212	37,693	$ 37,916
Funded status at December 31	$ (8,337)	$ (8,753)