Pension Information - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Pension plan eligibility age of employees	20 years 6 months
Pension plan eligibility service period of employees	6 months
Pension plan eligibility service hours of employees	1000 hours
Additional benefits under pension plan	$ 0
Defined benefit plan, benefit obligation	4,039,000
Accumulated other comprehensive income (loss)	2,666,000
Expected future employer contributions	1,515,000
Employer contributions		4,900,000
Employer settlements of several retirements		$ 3,000,000