Investment Securities (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Schedule of Investments [Line Items]
Investment Securities average remaining life	4 years 8 months
Available-for-sale Securities and Held-to-maturity Securities	0	0
Other than Temporary Impairment Losses, Investments	$ 0	$ 0
Asset backed securities mortgage portfolio, term	15 years
U.S. Treasury And Sponsored Entities Callable Notes [Member]
Schedule of Investments [Line Items]
Available for Sale expected to be called	100,600,000
Available-for-sale securities	$ 495,200,000
U.S. Treasury And Sponsored Entities Callable Notes [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Available for Sale Securities, Debt Maturities, Term	5 years
U.S. Treasury And Sponsored Entities Callable Notes [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Available for Sale Securities, Debt Maturities, Term	8 years