Balance Sheet - Parent Company Only (Additional Information) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Treasury Stock, Value	[1]	$ 2,346	$ 1,658
Treasury Stock and Other
Treasury Stock, Value		2,448	1,764	$ 1,119
Deferred Compensation Equity		1	2	$ 21
Parent Company [Member]
Treasury Stock, Value	[2]	2,449	1,766
Parent Company [Member] | Treasury Stock and Other
Treasury Stock, Value		2,448	1,764
Deferred Compensation Equity		$ 1	$ 2

[1] Includes noncontrolling interest of $103 million and $108 million at December 31, 2016 and December 31, 2015, respectively.

[2] At December 31, 2016, includes ($2,448) million for treasury stock and ($1) million for compensation element of restricted stock.At December 31, 2015, includes ($1,764) million for treasury stock and ($2) million for compensation element of restricted stock.