Employee Benefit Plans - Additional Information (Detail) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
Compensation and Retirement Disclosure [Abstract]
Unrecognized prior service costs, before tax	$ 1
Unrecognized prior service costs, net of tax	1
Unrecognized actuarial losses, before tax	58,576
Unrecognized actuarial losses, net of tax	38,074
Future Amortization of Prior Service Cost, before tax	1
Future Amortization of Prior Service Cost, net of tax	1
Amortization of actuarial losses, before tax, expected for fiscal year ended December 31, 2014	4,900
Amortization of actuarial losses, net of tax, expected for fiscal year ended December 31, 2014	$ 3,185