Pension and Other Postretirement Employee Benefit Plans - One Percentage Point Increase Effects (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Effect of a one-percentage-point change in the assumed health care cost trend rate on the Firms total service and interest cost and accumulated postretirement benefit obligation
Effect on accumulated postretirement benefit obligation, 1-Percentage-point increase	$ 8
Effect on accumulated postretirement benefit obligation, 1-Percentage-point decrease	(7)
Pension and other postretirement employee benefit plans, U.S.
Effect of a one-percentage-point change in the assumed health care cost trend rate on the Firms total service and interest cost and accumulated postretirement benefit obligation
Aggregate increase from 25-basis point decline	39
Aggregate expense from a 25-basis point decline	31
Increase in related benefit obligations from a 25-basis point decline	296
Decrease in related PBO from a 25-basis point decrease	145
U.S. defined benefit pension plans
Effect of a one-percentage-point change in the assumed health care cost trend rate on the Firms total service and interest cost and accumulated postretirement benefit obligation
Decrease in pension expense from a 25-basis point decrease	35
Non-U.S. pension and other postretirement employee benefit plans
Effect of a one-percentage-point change in the assumed health care cost trend rate on the Firms total service and interest cost and accumulated postretirement benefit obligation
Increase in plan expense from a 25-basis point decline	$ 17