Employee Pension Benefits - Components of Net Periodic Pension Benefit of Pension Plan and Excess Pension Plan (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Compensation and Retirement Disclosure [Abstract]
Interest cost	$ 506	$ 425	$ 1,012	$ 877
Expected return on assets	(1,312)	(1,076)	(2,624)	(2,173)
Recognized net actuarial loss	0	468	0	1,012
Amortization of prior service (credit)	(388)	(389)	(777)	(778)
Net periodic pension benefit (income)	$ (1,194)	$ (572)	$ (2,389)	$ (1,062)