Other Comprehensive Income/Loss (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net unrealized gain on securities available-for-sale before tax amount:
Net unrealized holding gain on securities available-for-sale arising during the period	$ 7,263	$ (10,396)	$ 11,891	$ (10,196)
Reclassification adjustment for gain on sales of securities included in net income		(2,057)		(2,057)
Net unrealized loss on securities available-for-sale		(12,453)		(12,253)
Net actuarial loss adjustment on pension plans and other postretirement benefits before tax amount:
Reclassification adjustment for net actuarial loss included in net income	249	838	457	1,805
Prior service cost adjustment on pension plans and other postretirement benefits before tax amount:
Reclassification adjustment for prior service cost included in net income	48	53	95	106
Total other comprehensive income, before tax amount	7,560	(11,562)	12,443	(10,342)
Net unrealized gain on securities available-for-sale, tax expense:
Net unrealized holding gain on securities available-for-sale arising during the period	(2,564)	3,663	(4,199)	3,593
Reclassification adjustment for gains included in net income		725		725
Net unrealized loss on securities available-for-sale		4,388		4,318
Net actuarial loss adjustment on pension plans and other postretirement benefits, tax expense:
Reclassification adjustment for net actuarial loss included in net income	(88)	(296)	(161)	(636)
Prior service cost adjustment on pension plans and other postretirement benefits, tax expense:
Reclassification adjustment for prior service cost included in net income	(17)	(18)	(34)	(37)
Total other comprehensive income, tax expense	(2,669)	4,074	(4,394)	3,645
Net unrealized gain on securities available-for-sale:
Net unrealized holding gain on securities available-for-sale arising during the period	4,699	(6,733)	7,692	(6,603)
Reclassification adjustment for gains included in net income		(1,332)		(1,332)
Net unrealized gain (loss) on securities available-for-sale	4,699	(8,065)	7,692	(7,935)
Net actuarial loss adjustment on pension plans and other postretirement benefits:
Reclassification adjustment for net actuarial loss included in net income	161	542	296	1,169
Prior service cost adjustment on pension plans and other postretirement benefits:
Reclassification adjustment for prior service cost included in net income	31	35	61	69
Total other comprehensive income (loss), net of tax	$ 4,891	$ (7,488)	$ 8,049	$ (6,697)