Pension Plans and Defined Contribution Plan - Schedule of Change in Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 162,977
Benefits paid	(2,952)	$ (6,343)
Fair value of plan assets at end of year	142,088	162,977
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	162,977	173,771
Actual return on plan assets	12,136	(6,451)
Company contributions	10,000	2,000
Benefits paid	(2,952)	(6,343)
Settlements	(40,073)
Fair value of plan assets at end of year	$ 142,088	$ 162,977