Other Comprehensive Income/Loss (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net unrealized gain on securities available-for-sale before tax amount:
Net unrealized loss on securities available-for-sale	$ 3,223	$ 4,628
Net actuarial loss adjustment on pension plans and other postretirement benefits before tax amount:
Reclassification adjustment for net actuarial loss included in net income	757	208
Prior service cost adjustment on pension plans and other postretirement benefits before tax amount:
Reclassification adjustment for prior service cost included in net income	47	47
Total other comprehensive income, before tax amount	4,027	4,883
Net unrealized gain on securities available-for-sale, tax expense:
Net unrealized loss on securities available-for-sale	(1,230)	(1,635)
Net actuarial loss adjustment on pension plans and other postretirement benefits, tax expense:
Reclassification adjustment for net actuarial loss included in net income	(288)	(73)
Prior service cost adjustment on pension plans and other postretirement benefits, tax expense:
Reclassification adjustment for prior service cost included in net income	(18)	(17)
Total other comprehensive income, tax expense	(1,536)	(1,725)
Net unrealized gain on securities available-for-sale:
Net unrealized gain on securities available-for-sale arising during the period	1,993	2,993
Reclassification adjustment for net actuarial loss on pension plans and other postretirement benefits included in net income	469	135
Prior service cost adjustment on pension plans and other postretirement benefits:
Reclassification adjustment for prior service cost included in net income	29	30
Total other comprehensive income, net of tax	$ 2,491	$ 3,158