Retirement-Related Benefits - Net Funded Status (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Net funded status recognized in the Consolidated Statement of Financial Position
Prepaid pension assets	$ 4,666	$ 4,643
Current liabilities - compensation and benefits	(3,310)	(3,644)
Noncurrent liabilities - retirement and nonpension postretirement benefit obligations	(17,002)	(16,720)
Pension Plans \| U.S.
Net funded status recognized in the Consolidated Statement of Financial Position
Prepaid pension assets	2,069	2,092
Current liabilities - compensation and benefits	(120)	(120)
Noncurrent liabilities - retirement and nonpension postretirement benefit obligations	(1,548)	(1,722)
Funded Status	401	250
Pension Plans \| Non-U.S.
Net funded status recognized in the Consolidated Statement of Financial Position
Prepaid pension assets	2,597	2,551
Current liabilities - compensation and benefits	(302)	(323)
Noncurrent liabilities - retirement and nonpension postretirement benefit obligations	(11,306)	(10,541)
Funded Status	(9,012)	(8,312)
Nonpension Postretirement Plans \| U.S.
Net funded status recognized in the Consolidated Statement of Financial Position
Prepaid pension assets	0	0
Current liabilities - compensation and benefits	(340)	(353)
Noncurrent liabilities - retirement and nonpension postretirement benefit obligations	(3,542)	(3,812)
Funded Status	(3,882)	(4,165)
Nonpension Postretirement Plans \| Non-U.S.
Net funded status recognized in the Consolidated Statement of Financial Position
Prepaid pension assets	0	0
Current liabilities - compensation and benefits	(36)	(17)
Noncurrent liabilities - retirement and nonpension postretirement benefit obligations	(605)	(646)
Funded Status	$ (640)	$ (663)

Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

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