Employee Retirement and Postretirement Benefits - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014 Plans	Mar. 31, 2013	Jul. 31, 2013 Board of Directors Chairman [Member]	Jul. 31, 2013 Director [Member]	Jul. 31, 2013 Chairman Of Audit Committee [Member]	Jul. 31, 2013 Chairman Of Compensation Committee [Member]	Jul. 31, 2013 Chairman Of Nominating And Governance Committee [Member]	Mar. 31, 2014 Restricted Stock [Member]	Mar. 31, 2014 Deferred Stock [Member] Director [Member]
Employee Benefit Plans [Line Items]
Stock Options, Shares Granted	25,061
Stock Options, Shares Forfeited	24,370
Stock Options, Shares Expired	15,349
Stock Options, Shares Exercised	64,168
Number of share based compensation plans	2
Share units granted								18,908	5,844
Stock compensation expense	$ 1,604,000	$ 878,000
Maximum percentage of annual gross salary allowable	15.00%
Employee Contribution	100.00%
Percentage of employees contribution matched by the company	4.00%
Employer Contribution	600,000
Compensation to non employee directors			225,000	150,000
Description of Board of Directors compensation payment method	Compensation is to be paid 1/3 in cash, 1/3 in stock options and 1/3 in deferred share units ("DSUs").
Additional compensation to non employee directors					$ 20,000	$ 10,000	$ 5,000