Employee Benefit Plans Defined Benefit Plan, Change in Obligations and Fair Value (Additional Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Other Assets		$ 5,582	$ 5,656
Other Liabilities		$ 3,198	$ 3,321
Pension Plan [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	[1]	4.44%	4.09%
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities		$ 81	$ 85
Defined Benefit Plan, Contributions by Employer	[1]	5	6
Common Stock held in Pension Plan		1	1
Other Assets		244	230
Other Liabilities		$ 81	$ 85
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.95%	3.60%
Defined Benefit Plan, Contributions by Employer		$ 0	$ 0
Other Assets		$ 91	$ 91

[1] Employer contributions represent the benefits that were paid to nonqualified plan participants. Unfunded nonqualified supplemental pension plans are not funded through plan assets.