Balance Sheet - Parent Company Only (Additional Information) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Treasury Stock, Value	[1]	$ 1,658	$ 1,032
Treasury Stock and Other
Treasury Stock, Value		1,764	1,119	$ 684
Deferred Compensation Equity		$ 2	$ 21	$ 50

[1] Includes noncontrolling interest of $108 million and $108 million at December 31, 2015 and December 31, 2014, respectively.