Investments (Schedule Of Available-For-Sale Securities Whose Value Is Below Amortized Cost) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013 security		Dec. 31, 2012 security
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Fair Value	$ 81,142		$ 82,901
Gross Unrealized Losses	1,040		320
Number of Securities	1,331		626
Fair Value Decline, Greater Than 20% [Member]
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Fair Value	512		444
Gross Unrealized Losses	165		198
Gross Unrealized OTTI	96		129
Number of Securities	132	[1]	148	[1]
Fair Value Decline, Greater Than 20% [Member] | Less Than Six Months [Member]
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Fair Value	227		34
Gross Unrealized Losses	71		9
Gross Unrealized OTTI	7		1
Number of Securities	29	[1]	14	[1]
Fair Value Decline, Greater Than 20% [Member] | Six Months Or Greater, But Less Than Nine Months [Member]
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Number of Securities	5	[1]
Fair Value Decline, Greater Than 20% [Member] | Nine months or greater, but less than twelve months
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Fair Value			15
Gross Unrealized Losses			10
Number of Securities	1	[1]	3	[1]
Fair Value Decline, Greater Than 20% [Member] | Twelve Months Or Greater [Member]
Available For Sale Securities In Unrealized Loss Position With Loss Severity Greater Than 20 Percent [Line Items]
Fair Value	285		395
Gross Unrealized Losses	94		179
Gross Unrealized OTTI	$ 89		$ 128
Number of Securities	97	[1]	131	[1]

[1] We may reflect a security in more than one aging category based on various purchase dates.