Company's Pension and Post-Retirement Plans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits
Components of net periodic (credit) expense:
Interest cost	$ 1,474	$ 1,364	$ 2,948	$ 2,728
Service cost	0	0	0	0
Expected return on plan assets	(4,859)	(4,147)	(9,718)	(8,294)
Amortization of prior-service costs	0	0	0	0
Amortization of net actuarial loss	822	2,351	1,644	4,702
Net periodic (credit) expense	(2,563)	(432)	(5,126)	(864)
Post-Retirement Benefits
Components of net periodic (credit) expense:
Interest cost	190	171	380	342
Service cost	1	1	2	2
Expected return on plan assets	0	0	0	0
Amortization of prior-service costs	(62)	(62)	(124)	(124)
Amortization of net actuarial loss	118	164	236	328
Net periodic (credit) expense	$ 247	$ 274	$ 494	$ 548