Equity (Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Class of Stock [Line Items]
Unrealized gains (losses) on derivative instruments designated as cash flow hedges, beginning balance	$ (12,524)	$ (1,208)	$ 19,242
Unrealized gains (losses) on derivative instruments designated as cash flow hedges, period changes, net of tax	(849)	(11,316)	(20,450)
Unrealized gains (losses) on derivative instruments designated as cash flow hedges, ending balance	(13,373)	(12,524)	(1,208)
Unrealized gains (losses) on investment securities available for sale, beginning balance	33,617	58,366	67,084
Unrealized gains (losses) on investment securities available for sale, period change, net of tax	(16,506)	(24,749)	(8,718)
Unrealized gains (losses) on investment securities available for sale, ending balance	17,111	33,617	58,366
Post-retirement unfunded health benefit, beginning balance	0	0	(1,520)
Post-retirement unfunded health benefit, period change, net of tax	363	0	1,520
Post-retirement unfunded health benefit, ending balance	363	0	0
Accumulated other comprehensive income, beginning balance	21,093	57,158	84,806
Accumulated other comprehensive income, period change, net of tax	(16,992)	(36,065)	(27,648)
Accumulated other comprehensive income, ending balance	$ 4,101	$ 21,093	$ 57,158