Pension and Postretirement Benefits - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
Funded Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Amount expected to be contributed to funded pension plans	$ 2,600,000
Amount contributed to pension plans	2,300,000
Unfunded Pension Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Amount contributed to pension plans	665,000
Amount expected to contributed to unfunded pension plans	1,100,000
Postretirement Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Amount expected to be contributed to postretirement benefit plans	400,000
Amount contributed to postretirement benefit plans	$ 64,000