Income Taxes (Schedule of Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at January 1,	$ 88	$ 123	$ 114
Additions based on tax positions related to the current year	13	17	20
Additions for tax positions of previous years	1	6	11
Reductions for tax positions of prior years	(7)	(42)	(3)
Reductions due to lapse of statute of limitations	(14)	(7)	(8)
Settlements	(2)	(1)	(3)
Other	0	(8)	(8)
Balance at December 31,	$ 79	$ 88	$ 123