Derivative Instruments (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months	$ 447,000
Remaining unamortized deferred gain (loss) balance of all previously terminated cash flow hedges	(1,800,000)		(2,000,000)
Remaining deferred gain (loss) balance on all previously terminated fair value hedges	12,200,000		13,900,000
Gain (loss) on sale of outstanding commitments	7,400,000		(100,000)
Fixed Rate Residential Mortgage [Member]
Derivative [Line Items]
Commitments to fund fixed-rate mortgage loans	133,500,000		158,000,000
Unrealized gain on fair value of fixed-rate mortgage loans to customers	(2,500,000)	2,000,000
Sale of outstanding commitments	200,500,000		231,500,000
Interest Rate Swap [Member] | Customer Related Interest Rate Risk [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	1,130,000,000		2,800,000
Federal Funds Sold [Member]
Derivative [Line Items]
Federal funds sold	84,600,000
Federal Funds Sold, Counterparty with CCC [Member]
Derivative [Line Items]
Federal funds sold	$ 734,000