Accumulated Other Comprehensive Income - Schedule of Reclassification Out of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment charges	$ 1,240	$ 528	$ 1,256
Income tax expense	(4,626)	16,945	(5,413)
Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(1,180)	(575)	(825)
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Securities Available for Sale [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gains (losses) on securities transactions			21
Other-than-temporary impairment charges	(1,240)	(528)	(368)
Income tax expense	508	216	143
Net of tax	(732)	(312)	(204)
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net actuarial loss	(966)	(671)	(966)
Amortization of prior service cost	216	233	216
Income tax expense	301	174	130
Net of tax	$ (449)	$ (264)	$ (620)