Employee Benefit Plans - Schedule of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Compensation And Retirement Disclosure [Abstract]
Benefit cost, Interest cost	$ 435	$ 493	$ 870	$ 986
Benefit cost, Expected return on plan assets	(551)	(587)	(1,101)	(1,173)
Benefit cost, Recognized actuarial loss	580	1,007	1,159	2,013
Benefit cost, Settlement cost	144		423
Total net periodic benefit cost	$ 608	$ 913	$ 1,351	$ 1,826