Pension, Other Postretirement Benefits and Savings Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements Curtailments And Termination Benefits	$ (33)	$ 0	$ (1)
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Contributions to defined contribution savings plans	112	106	97
Current assets	7,724	8,644
Current liabilities	(4,736)	(5,025)
U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	(257)	(1,181)
Defined Benefit Plan, Accumulated Benefit Obligation	6,495	5,966
Plan Assets, Fair Value	(6,250)	(4,800)
Pension Contributions				1,167
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	15	45	39
Interest cost	256	243	261
Expected return on plan assets	(311)	(335)	(299)
Amortization of prior service cost (credit)	1	17	23
Amortization of net losses	114	205	179
Net periodic cost	75	175	203
Curtailments/settlements	32	0	1
Termination benefits	0	0	0
Total benefits (credit)	107	175	204
Prior service cost (credit) from plan amendments	(1)	(30)	0
Increase (decrease) in net actuarial losses	292	(374)	665
Amortization of prior service (cost) credit in net periodic cost	(1)	(17)	(23)
Amortization of net losses in net periodc cost	(114)	(205)	(179)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements and divestitures	(32)	0	(1)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	144	(626)	462
Amount Recognized in Net Periodic Benefit Cost and Other Comprehensive (Income) Loss, before Tax	251	(451)	666
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Noncurrent assets	9	51
Current liabilities	(10)	(12)
Noncurrent liabilities	(256)	(1,220)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(257)	(1,181)
U.S. hourly pension plans
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions				907
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements Curtailments And Termination Benefits				33
France Amiens Plant Closure Curtailment [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements Curtailments And Termination Benefits	22
Lump sum payments to settle U.K. pension plan obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements Curtailments And Termination Benefits				(5)
Annuity Purhcase to settle U.K. pension plan obligations
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements Curtailments And Termination Benefits			9
U.S. Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	(190)	(206)
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Total benefits (credit)	(24)	(24)	(17)
Non-U.S. Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	(166)	(177)
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Total benefits (credit)	9	15	17
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	(457)	(674)
Defined Benefit Plan, Accumulated Benefit Obligation	3,040	3,008
Plan Assets, Fair Value	(2,721)	(2,455)
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	34	39	31
Interest cost	131	131	143
Expected return on plan assets	(118)	(111)	(117)
Amortization of prior service cost (credit)	1	1	2
Amortization of net losses	35	50	45
Net periodic cost	83	110	104
Curtailments/settlements	(13)	4	11
Termination benefits	0	0	1
Total benefits (credit)	70	114	116
Prior service cost (credit) from plan amendments	1	(1)	6
Increase (decrease) in net actuarial losses	(78)	(128)	372
Amortization of prior service (cost) credit in net periodic cost	(1)	(1)	(2)
Amortization of net losses in net periodc cost	(36)	(53)	(43)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements and divestitures	(16)	(3)	(11)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(130)	(186)	322
Amount Recognized in Net Periodic Benefit Cost and Other Comprehensive (Income) Loss, before Tax	(60)	(72)	438
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Noncurrent assets	274	59
Current liabilities	(24)	(25)
Noncurrent liabilities	(707)	(708)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(457)	(674)
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	(356)	(383)
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	6	6
Interest cost	19	19	24
Expected return on plan assets	(1)	(1)	(1)
Amortization of prior service cost (credit)	(45)	(45)	(40)
Amortization of net losses	8	12	11
Net periodic cost	(15)	(9)	0
Curtailments/settlements	0	0	0
Termination benefits	0	0	0
Total benefits (credit)	(15)	(9)	0
Prior service cost (credit) from plan amendments	0	0	(82)
Increase (decrease) in net actuarial losses	3	(51)	(4)
Amortization of prior service (cost) credit in net periodic cost	45	47	40
Amortization of net losses in net periodc cost	(8)	(13)	(11)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements and divestitures	0	0	0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	40	(17)	(57)
Amount Recognized in Net Periodic Benefit Cost and Other Comprehensive (Income) Loss, before Tax	25	(26)	(57)
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Noncurrent assets	0	0
Current liabilities	(28)	(33)
Noncurrent liabilities	(328)	(350)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(356)	(383)
Prior Service Cost | Other Postretirement Benefit Plans
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Loss in Next Fiscal Year	(45)
Net Actuarial Loss | U.S.
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Loss in Next Fiscal Year	(110)
Net Actuarial Loss | Non-U.S. Other Postretirement Benefit Plans
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Loss in Next Fiscal Year	8
Net Actuarial Loss | Non-U.S.
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Loss in Next Fiscal Year	(37)
Discretionary Contributions | Frozen U.S. Pension Plans of US Entity
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions					834
Required Contributions | Frozen U.S. Pension Plans of US Entity
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions					34
Certain Unfunded Non US Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	288	303
Pension Savings and Other Postretirement Benefit Plans (Textuals) [Abstract]
Defined Benefit Plan, Benefit Obligation	348	352
Equity Securities | U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	6.00%
Equity Securities | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	15.00%
Fixed Income Securities [Member] | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	75.00%
Equity Securities, Equity Collars | U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan Assets, Fair Value		129
Debt Securities, Interest Rate Swaptions | U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan Assets, Fair Value		125
Minimum
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	50
Maximum
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ 75