Investment Securities (Narrative) (Details) (USD $)	9 Months Ended			3 Months Ended						3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 U.S. Treasury And Sponsored Entities Callable Notes [Member]	Sep. 30, 2012 U.S. Government Sponsored Entities Asset-Backed Securities [Member]	Sep. 30, 2011 U.S. Government Sponsored Entities Asset-Backed Securities [Member]	Jun. 30, 2011 U.S. Government Sponsored Entities Asset-Backed Securities [Member]	Mar. 31, 2011 U.S. Government Sponsored Entities Asset-Backed Securities [Member]	Sep. 30, 2012 U.S. Government Sponsored Entities Asset-Backed Securities [Member] Minimum [Member]	Sep. 30, 2012 U.S. Government Sponsored Entities Asset-Backed Securities [Member] Maximum [Member]	Mar. 31, 2011 Obligations Of States And Political Subdivisions [Member]	Sep. 30, 2011 Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Other than Temporary Impairment Losses, Investments	$ 54,000	$ 0
Asset backed securities mortgage portfolio, term	15 years
Available-for-sale securities			696,000,000
Residential mortgage-backed securities and collateralized mortgage obligations, term								9 years	15 years
Proceeds from Sale of Available-for-sale Securities, Debt				0	212,800,000	191,000,000	105,400,000				1,000,000
Pre-tax gain on sale of securities					$ 3,500,000	$ 15,400,000	$ 6,600,000			$ 0