Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Unrecognized prior service costs, before tax	$ 3
Unrecognized prior service costs, net of tax	2
Unrecognized actuarial losses, before tax	56,921
Unrecognized actuarial losses, net of tax	36,999
Amortization of transition asset, before tax, expected for fiscal year ended December 31, 2013	1
Amortization of transition asset, net of tax, expected for fiscal year ended December 31, 2013	1
Amortization of actuarial losses, before tax, expected for fiscal year ended December 31, 2013	4,693
Amortization of actuarial losses, net of tax, expected for fiscal year ended December 31, 2013	$ 3,050