Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss) by Component (Net of Income Taxes)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	$ 2,787		$ 4,101
Other comprehensive income (loss) before reclassifications	(35,059)		(36,390)
Amounts reclassified from accumulated other comprehensive income (loss)	(788)		(771)
Net current period other comprehensive income (loss)	(35,847)	9,198	(37,161)	(14,090)
Ending balance	(33,060)		(33,060)
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	(13,304)		(13,373)
Other comprehensive income (loss) before reclassifications	0		0
Amounts reclassified from accumulated other comprehensive income (loss)	67		136
Net current period other comprehensive income (loss)	67		136
Ending balance	(13,237)		(13,237)
Net Unrealized Gains (Losses) on Investment Securities Available for Sale [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	15,751		17,111
Other comprehensive income (loss) before reclassifications	(35,578)		(36,909)
Amounts reclassified from accumulated other comprehensive income (loss)	(862)		(891)
Net current period other comprehensive income (loss)	(36,440)		(37,800)
Ending balance	(20,689)		(20,689)
Amortization of Post-Retirement Unfunded Health Benefit [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward]
Beginning balance	340		363
Other comprehensive income (loss) before reclassifications	519		519
Amounts reclassified from accumulated other comprehensive income (loss)	7		(16)
Net current period other comprehensive income (loss)	526		503
Ending balance	$ 866		$ 866