Employee Pension Benefits - Schedule of Changes in Components of Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Compensation and Retirement Disclosure [Abstract]
Accumulated Other Comprehensive Income Before Tax - Beginning Balance			$ 5,032
Amortization of Prior service costs (credits)- Before Tax			(1,166)
Accumulated Other Comprehensive Income Before Tax - Ending Balance	3,866		3,866
Income Tax Benefit (Expense) - Beginning Balance			(1,886)
Amortization of Prior service costs (credits)- Tax Effect			452
Income Tax Benefit (Expense) - Ending Balance	(1,434)		(1,434)
Accumulated Other Comprehensive Income Net of Income Tax - Beginning Balance			3,146
Amortization of Prior service costs (credits)- Net of Income Tax	(238)	(238)	(714)	(714)
Accumulated Other Comprehensive Income Net of Income Tax - Ending Balance	$ 2,432		$ 2,432