Investment Securities (Narrative) (Details) (USD $)	6 Months Ended			3 Months Ended				6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 U.S. Treasury And Sponsored Entities Callable Notes [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]	Jun. 30, 2012 U.S. Government Sponsored Entities Asset-Backed Securities [Member] Minimum [Member]	Jun. 30, 2012 U.S. Government Sponsored Entities Asset-Backed Securities [Member] Maximum [Member]	Jun. 30, 2011 Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Other than Temporary Impairment Losses, Investments	$ 54,000	$ 0
Available-for-sale securities			490,000,000
Residential mortgage-backed securities and collateralized mortgage obligations, term						9 years	15 years
Proceeds from Sale of Available-for-sale Securities, Debt				191,000,000	105,400,000			1,000,000
Pre-tax gain on sale of securities				$ 15,400,000	$ 6,600,000