Debt And Lines Of Credit Debt and Lines of Credit (Summary of Long-Term Debt Footnotes) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2007
Debt Instrument [Line Items]
Long-term debt					$ 2,140,000,000
Debt Instrument, Fair Value Disclosure	10,600,000,000		10,700,000,000
Variable Rate [Domain]
Debt Instrument [Line Items]
Original maturity date range, maximum	2017		2017
Debt instrument, interest rate during period	2.80%		2.60%
Long-term debt	271,000,000	[1]	269,000,000	[1]
Municipal Bonds [Member]
Debt Instrument [Line Items]
Original maturity date range, maximum	2035		2035
Debt instrument, interest rate during period	5.70%		5.50%
Long-term debt	950,000,000	[2]	1,487,000,000	[2]
Short-term Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate during period	2.60%		2.80%
Foreign Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate during period	7.20%		5.80%
Long-term debt	91,000,000		93,000,000
Long-term Debt [Member]
Debt Instrument [Line Items]
Long-term debt	275,000,000	[3]	304,000,000	[3]
Interest Rate Swap Unwind [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Deferred gain (loss) on discontinuation of interest rate fair value hedge	$ 20,000,000		$ 41,000,000

[1] The weighted average interest rate on these notes was 2.8% in 2014 and 2.6% in 2013.

[2] The weighted average interest rate on these bonds was 5.7% in 2014 and 5.5% in 2013.

[3] Includes $20 million at December 31, 2014 and $41 million at December 31, 2013, related to the unamortized gain on interest rate swap unwinds (see Note 14).