Short-Term and Long-Term Debt (Schedule of Extinguishment of Debt) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Principal balance outstanding prior to payoff	$ 350	[1]
Unamortized debt issuance costs and discounts prior to payoff	(3)
Amount paid to retire	(410)
Gain (loss) on extinguishment of debt, pre-tax	$ (63)

[1] During the fourth quarter of 2016, we repurchased $200 million of our 8.75% senior notes due 2019 and $150 million of our 6.15% senior notes due 2036.