Accumulated Other Comprehensive Income Changes in Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Unrealized gain on securities, before tax amount	$ (5,505)	$ 12,088	$ 40,441	$ 8,987
Unrealized gain on securities, tax effect	1,925	(4,231)	(14,156)	(3,146)
Unrealized gain on securities, net of tax amount	(3,580)	7,857	26,285	5,841
Reclassification adjustment for securities gains included in net income, before tax amount	(2)	(1,730)	(1,025)	(8,290)
Reclassification adjustment for securities gains included in net income, tax effect	1	606	359	2,902
Reclassification adjustment for securities gains included in net income, net of tax amount	(1)	(1,124)	(666)	(5,388)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax		3,778		3,778
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax		(1,322)		(1,322)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0	(2,456)	0	(2,456)
Non-credit related unrealized gains on other-than-temporarily impaired debt securities, before tax amount				192
Non-credit related unrealized gains on other-than-temporarily impaired debt securities, tax effect				(67)
Non-credit related unrealized gains on other-than-temporarily impaired debt securities, net of tax amount	0	0	0	125
Amortization of unrealized loss on derivative financial instruments, before tax amount	6	5	18	110
Amortization of unrealized loss on derivative financial instruments, tax effect	(2)	(2)	(6)	(39)
Amortization of unrealized loss on derivative financial instruments, net of tax amount	4	3	12	71
Amortization of net unrecognized pension and postretirement items, before tax amount	583	717	1,349	2,151
Amortization of net unrecognized pension and postretirement items, tax effect	(204)	(251)	(472)	(753)
Amortization of net unrecognized pension and postretirement items, net of tax amount	379	466	877	1,398
Total Other Comprehensive Income, Before Tax Amount	(4,918)	14,858	40,783	6,928
Total Other Comprehensive Income, Tax Effect	1,720	(5,200)	(14,275)	(2,425)
Other Comprehensive (Loss) Income	$ (3,198)	$ 9,658	$ 26,508	$ 4,503