Pension Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in benefit obligation:
Benefit obligation at beginning of year	$ 18,752	$ 18,326	$ 16,191
Service cost	1,170	1,094	989
Interest	763	800	890
Actuarial (gain) loss	(1,540)	27	401
Benefits paid	(106)	(1,495)	(145)
Benefit obligation at end of year	19,039	18,752	18,326
Change in plan assets:
Balance at beginning of year	12,200	11,377	10,950
Actual return (loss) on plan assets	992	818	(28)
Employer contribution	725	1,500	600
Benefits paid	(106)	(1,495)	(145)
Balance at end of year	13,811	12,200	11,377
Funded status and accrued benefit at end of year	5,228	6,552	6,949
Accumulated benefit obligation at end of year	$ 13,192	$ 13,297	$ 11,964