Pension and Employee Benefit Plans - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions	$ 0	$ 29,000
Unfunded liability plans	11,100,000		$ 11,100,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Anticipated contribution to fund the pension plan during the reminder of the fiscal year	2,000,000
Health Care Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Anticipated contribution to fund the pension plan during the reminder of the fiscal year	$ 25,000