Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains and losses on available for sale securities, Before tax amount	$ 5,460	$ 916	$ 158
Unrealized gains and losses on available for sale securities, Tax (expense) benefit	1,556	(35)	(35)
Amortization of prior service cost included in net periodic pension cost, Before tax amount	426	(1,019)	474
Direct Cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service cost included in net periodic pension cost, Before tax amount	146	32	37
Amortization of prior service cost included in net periodic pension cost, Tax (expense)benefit	(27)	(6)	(137)
Amortization of prior service cost included in net periodic pension cost, Net of tax	119	26	(100)
Other Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains and losses on available for sale securities, Before tax amount	(942)	(269)	(448)
Unrealized gains and losses on available for sale securities, Tax (expense) benefit	244	175	188
Unrealized gains and losses on available for sale securities, Net of tax	$ (698)	$ (94)	$ (260)