Benefit Plans - Components of Accumulated Other Comprehensive Loss (Gain) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost	$ 0	$ 0
Unrecognized net actuarial gain	7,699	15,871
Total accumulated other comprehensive loss (gain)	7,699	15,871
Post-retirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost	(5)	(9)
Unrecognized net actuarial gain	(4,076)	(434)
Total accumulated other comprehensive loss (gain)	$ (4,081)	$ (443)