Securities Sold Under Agreements To Repurchase (Schedule Of Long Term Securities Sold Under Agreements To Repurchase) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
Derivative interest rate	8.00%
No. of agreements	27
Amount	$ 1,400,000,000
Weighted average rate	4.14%
Fixed To Floating 150.0 [Member] | Fixed-To-Floating [Member]
Maximum rate	3.75%
Minimum rate	0.00%
No. of agreements	3
Amount	150,000,000
Weighted average rate	3.75%
Final maturity	2014
Fixed To Floating 250.0 [Member] | Fixed-To-Floating [Member]
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	5
Amount	250,000,000
Weighted average rate	3.50%
Final maturity	2014
Fixed To Floating 200.0 [Member] | Fixed-To-Floating [Member]
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	4
Amount	200,000,000
Weighted average rate	3.50%
Final maturity	2015
Fixed To Floating 50.0 [Member] | Fixed-To-Floating [Member]
Maximum rate	3.25%
Minimum rate	0.00%
No. of agreements	1
Amount	50,000,000
Weighted average rate	3.25%
Final maturity	2015
Floating-To-Fixed 550.0 [Member] | Floating-To-Fixed [Member]
No. of agreements	10
Amount	550,000,000
Weighted average rate	4.54%
Final maturity	2014
Floating-To-Fixed 200.0 [Member] | Floating-To-Fixed [Member]
No. of agreements	4
Amount	$ 200,000,000
Weighted average rate	5.00%
Final maturity	2017