Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss) by Component (Net of Income Taxes)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	$ (3,651)	$ (30,463)	$ (12,605)	$ (41,258)
Other comprehensive income (loss) before reclassifications	(17,493)	16,723	(8,136)	28,311
Amounts reclassified from accumulated other comprehensive income (loss)	(1,179)	24	(1,582)	(769)
Net current period other comprehensive income (loss)	(18,672)	16,747	(9,718)	27,542
Ending balance	(22,323)	(13,716)	(22,323)	(13,716)
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	(12,755)	(13,030)	(12,824)	(13,099)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	68	68	137	137
Net current period other comprehensive income (loss)	68	68	137	137
Ending balance	(12,687)	(12,962)	(12,687)	(12,962)
Net Unrealized Gains (Losses) on Investment Securities Available for Sale [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	8,198	(18,166)	(713)	(28,936)
Other comprehensive income (loss) before reclassifications	(17,636)	16,480	(8,279)	28,068
Amounts reclassified from accumulated other comprehensive income (loss)	(1,221)	0	(1,667)	(818)
Net current period other comprehensive income (loss)	(18,857)	16,480	(9,946)	27,250
Ending balance	(10,659)	(1,686)	(10,659)	(1,686)
Post-Retirement Unfunded Health Benefit [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	906	733	932	777
Other comprehensive income (loss) before reclassifications	143	243	143	243
Amounts reclassified from accumulated other comprehensive income (loss)	(26)	(44)	(52)	(88)
Net current period other comprehensive income (loss)	117	199	91	155
Ending balance	$ 1,023	$ 932	$ 1,023	$ 932