Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss) by Component (Net of Income Taxes)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	$ (22,323)	$ (13,716)	$ (12,605)	$ (41,258)
Other comprehensive income (loss) before reclassifications	16,220	(11,180)	8,084	17,131
Amounts reclassified from accumulated other comprehensive income (loss)	11	69	(1,571)	(700)
Net current period other comprehensive income (loss)	16,231	(11,111)	6,513	16,431
Ending balance	(6,092)	(24,827)	(6,092)	(24,827)
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	(12,687)	(12,962)	(12,824)	(13,099)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	69	69	206	206
Net current period other comprehensive income (loss)	69	69	206	206
Ending balance	(12,618)	(12,893)	(12,618)	(12,893)
Net Unrealized Gains (Losses) on Investment Securities Available for Sale [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	(10,659)	(1,686)	(713)	(28,936)
Other comprehensive income (loss) before reclassifications	16,220	(11,180)	7,941	16,888
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	(1,667)	(818)
Net current period other comprehensive income (loss)	16,220	(11,180)	6,274	16,070
Ending balance	5,561	(12,866)	5,561	(12,866)
Post-Retirement Unfunded Health Benefit [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	1,023	932	932	777
Other comprehensive income (loss) before reclassifications	0	0	143	243
Amounts reclassified from accumulated other comprehensive income (loss)	(58)	0	(110)	(88)
Net current period other comprehensive income (loss)	(58)	0	33	155
Ending balance	$ 965	$ 932	$ 965	$ 932