Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (15,027)	$ (51,159)	$ (64,440)	$ (52,981)
Other comprehensive loss before reclassifications		(722)	17,915	57,273	19,432
Amounts reclassified from accumulated other comprehensive income (loss)		965	(1,632)	(7,617)	(1,327)
Net current period other comprehensive (loss) income		243	16,283	49,656	18,105
Ending balance		(14,784)	(34,876)	(14,784)	(34,876)
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	0	(1,875)	(892)	(2,664)
Other comprehensive loss before reclassifications	[1]	0	421	892	1,210
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	0	0	0
Net current period other comprehensive (loss) income	[1]	0	421	892	1,210
Ending balance	[1]	0	(1,454)	0	(1,454)
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	31,213	2,604	(15,125)	5,098
Other comprehensive loss before reclassifications	[1]	(722)	17,494	56,381	18,222
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	(161)	(3,470)	(10,926)	(6,692)
Net current period other comprehensive (loss) income	[1]	(883)	14,024	45,455	11,530
Ending balance	[1]	30,330	16,628	30,330	16,628
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(46,240)	(51,888)	(48,423)	(55,415)
Other comprehensive loss before reclassifications	[1]	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	1,126	1,838	3,309	5,365
Net current period other comprehensive (loss) income	[1]	1,126	1,838	3,309	5,365
Ending balance	[1]	$ (45,114)	$ (50,050)	$ (45,114)	$ (50,050)

[1] All amounts are net of tax.