Pension and Other Postretirement Employee Benefit Plans - Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension plans, U.S.
Amortization:
Total defined contribution plans	$ 99	$ 89
Pension plans, Non-U.S.
Amortization:
Total defined contribution plans	86	83
Pension plans, U.S.
Components of net periodic benefit cost
Benefits earned during the period	73	85
Interest cost on benefit obligations	133	125
Expected return on plan assets	(222)	(232)
Amortization:
Net (gain)/loss	59	62
Prior service cost/(credit)	(9)	(9)
Net periodic defined benefit cost	34	31
Other defined benefit pension plans	3	3
Total defined benefit plans	37	34
Total pension and OPEB cost included in compensation expense	136	123
Pension plans, Non-U.S.
Components of net periodic benefit cost
Benefits earned during the period	9	9
Interest cost on benefit obligations	26	28
Expected return on plan assets	(36)	(38)
Amortization:
Net (gain)/loss	5	9
Prior service cost/(credit)	0	0
Net periodic defined benefit cost	4	8
Other defined benefit pension plans	2	5
Total defined benefit plans	6	13
Total pension and OPEB cost included in compensation expense	92	96
OPEB plans
Components of net periodic benefit cost
Benefits earned during the period	0	0
Interest cost on benefit obligations	8	8
Expected return on plan assets	(26)	(26)
Amortization:
Net (gain)/loss	0	0
Prior service cost/(credit)	0	0
Net periodic defined benefit cost	(18)	(18)
Total defined benefit plans	(18)	(18)
Total pension and OPEB cost included in compensation expense	$ (18)	$ (18)