Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (51,159)	$ 4,057	$ (52,981)	$ (25,268)
Other comprehensive income before reclassifications		17,915	(6,418)	19,432	20,954
Amounts reclassified from accumulated other comprehensive (loss) income		(1,632)	503	(1,327)	2,456
Net current period other comprehensive income		16,283	(5,915)	18,105	23,410
Ending balance		(34,876)	(1,858)	(34,876)	(1,858)
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(1,875)	(3,643)	(2,664)	(4,434)
Other comprehensive income before reclassifications	[1]	421	582	1,210	1,373
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	0	0	0	0
Net current period other comprehensive income	[1]	421	582	1,210	1,373
Ending balance	[1]	(1,454)	(3,061)	(1,454)	(3,061)
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	2,604	16,490	5,098	(10,091)
Other comprehensive income before reclassifications	[1]	17,494	(7,000)	18,222	19,581
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	(3,470)	0	(6,692)	0
Net current period other comprehensive income	[1]	14,024	(7,000)	11,530	19,581
Ending balance	[1]	16,628	9,490	16,628	9,490
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(51,888)	(8,790)	(55,415)	(10,743)
Other comprehensive income before reclassifications	[1]	0	0	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	1,838	503	5,365	2,456
Net current period other comprehensive income	[1]	1,838	503	5,365	2,456
Ending balance	[1]	$ (50,050)	$ (8,287)	$ (50,050)	$ (8,287)

[1] All amounts are net of tax.