Investment Securities (Schedule Of Maturities Of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Available-for-sale securities, three months or less, amortized cost	$ 24,868
Available-for-sale securities, over three months through twelve months, amortized cost	93,437
Available-for-sale securities, after one year through five years, amortized cost	1,818,751
Available-for-sale securities, after five years through ten years, amortized cost	302,574
Available-for-sale securities, after ten years, amortized cost	251,237
Available-for-sale securities, amortized cost	2,492,826
Available-for-sale securities, three months or less, fair value	24,960
Available-for-sale securities, over three months through twelve months, fair value	94,520
Available-for-sale securities, after one year through five years, fair value	1,837,341
Available-for-sale securities, after five years through ten years, fair value	308,125
Available-for-sale securities, after ten years, fair value	253,057
Available-for-sale securities, fair value	2,520,037
Held-to-maturity securities, three months or less, amortized cost	0
Held-to-maturity securities, over three months through twelve months, amortized cost	3
Held-to-maturity securities, after one year through five years, amortized cost	159
Held-to-maturity securities, after five years through ten years, amortized cost	358
Held-to-maturity securities, after ten years, amortized cost	3,782
Investment securities held to maturity	4,302	$ 4,609
Held-to-maturity securities, three months or less, fair value	0
Held-to-maturity securities, over three months through twelve months, fair value	3
Held-to-maturity securities, after one year through five years, fair value	474
Held-to-maturity securities, after five years through ten years, fair value	865
Held-to-maturity securities, after ten years, fair value	3,852
Held-to-maturity securities, fair value	5,194	$ 5,590
Other Investment Securities
Investment Holdings [Line Items]
Available-for-sale securities, amortized cost	1,959
Available-for-sale securities, fair value	2,034
Investment securities held to maturity	0
Held-to-maturity securities, fair value	$ 0