Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Operating loss carryforwards	$ 153
Tax credit carryforwards	100
Federal [Member]
Operating loss carryforwards	136	[1]
Tax credit carryforwards	72	[2]
Net operating loss carryforward, expiration period start	2028
Tax credit carryforward, expiration period start	2029
State [Member]
Operating loss carryforwards	17	[3]
Tax credit carryforwards	$ 28	[4]
Net operating loss carryforward, expiration period start	2017
Tax credit carryforward, expiration period start	2012

[1] These will begin to expire in 2028.

[2] These will begin to expire in 2029.

[3] These will begin to expire in 2017.

[4] These will begin to expire in 2012.