Employee Benefit Plans (Details 7) - Level 3 [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	$ 1,772	$ 1,641
Actual Return on Plan Assets:
Assets held at the reporting date	145	115
Assets sold during the period	23	20
Purchases, Sales and Settlements	11	(4)
Transfers in and/or out of Level 3	0	0
Ending Balance	1,951	1,772
Corporate [Member]
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	22	23
Actual Return on Plan Assets:
Assets held at the reporting date	(3)	0
Assets sold during the period	0	0
Purchases, Sales and Settlements	6	(1)
Transfers in and/or out of Level 3	0	0
Ending Balance	25	22
Mortgage-Backed Securities [Member]
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	0	2
Actual Return on Plan Assets:
Assets held at the reporting date	0	0
Assets sold during the period	0	0
Purchases, Sales and Settlements	0	(2)
Transfers in and/or out of Level 3	0	0
Ending Balance	0	0
Real Estate [Member]
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	1,693	1,559
Actual Return on Plan Assets:
Assets held at the reporting date	149	115
Assets sold during the period	23	20
Purchases, Sales and Settlements	7	(1)
Transfers in and/or out of Level 3	0	0
Ending Balance	1,872	1,693
Other [Member]
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	57	57
Actual Return on Plan Assets:
Assets held at the reporting date	(1)	0
Assets sold during the period	0	0
Purchases, Sales and Settlements	(2)	0
Transfers in and/or out of Level 3	0	0
Ending Balance	$ 54	$ 57