Pension and Employee Benefit Plans - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions	$ 400,000	$ 1,400,000
Unfunded liability plans	10,700,000		$ 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	200,000
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