Borrowings - Long-Term Debt, Components (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Borrowings
Long-term debt, gross	$ 45,708	$ 41,145
Less: net unamortized discount	837	839
Less: net unamortized debt issuance cost	92	82
Add: fair value adjustment	668	669
Long-term debt (including current maturities)	45,446	40,893
Less: current maturities	7,834	6,239
Long-term debt (excluding current portion)	37,612	34,655
IBM International Group Capital, LLC
Borrowings
Long-term debt, gross	$ 0
IBM International Group Capital, LLC
Borrowings
Ownership interest in subsidiary (as a percent)	100.00%
U.S. dollars
Borrowings
Long-term debt, gross	$ 32,339	30,563
Euros
Borrowings
Long-term debt, gross	$ 9,984	7,122
Debt instrument, average interest rate percentage (as a percent)	1.50%
Pound sterling
Borrowings
Long-term debt, gross	$ 1,364	1,296
Debt instrument, average interest rate percentage (as a percent)	2.70%
Japanese yen
Borrowings
Long-term debt, gross	$ 1,233	1,576
Debt instrument, average interest rate percentage (as a percent)	1.10%
Canadian
Borrowings
Long-term debt, gross		373
Debt instrument, average interest rate percentage (as a percent)	2.20%
Other
Borrowings
Long-term debt, gross	$ 788	215
Debt instrument, average interest rate percentage (as a percent)	8.50%
Maturing 2017 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 4,018	5,104
Debt instrument, average interest rate percentage (as a percent)	4.70%
Maturing 2018 Through 2019 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 8,934	8,856
Debt instrument, average interest rate percentage (as a percent)	3.25%
Maturing 2020 Through 2021 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 6,221	4,941
Debt instrument, average interest rate percentage (as a percent)	1.93%
Maturing 2022 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 2,903	1,901
Debt instrument, average interest rate percentage (as a percent)	2.40%
Maturing 2023 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 1,502	1,500
Debt instrument, average interest rate percentage (as a percent)	3.37%
Maturing 2024 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 2,000	2,000
Debt instrument, average interest rate percentage (as a percent)	3.63%
Maturing 2025 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 600	600
Debt instrument, average interest rate percentage (as a percent)	7.00%
Maturing 2026 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 1,350	1,350
Debt instrument, average interest rate percentage (as a percent)	3.45%
Maturing 2027 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 969	469
Debt instrument, average interest rate percentage (as a percent)	4.71%
Maturing 2028 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 313	313
Debt instrument, average interest rate percentage (as a percent)	6.50%
Maturing 2032 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 600	600
Debt instrument, average interest rate percentage (as a percent)	5.88%
Maturing 2038 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 83	83
Debt instrument, average interest rate percentage (as a percent)	8.00%
Maturing 2039 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 745	745
Debt instrument, average interest rate percentage (as a percent)	5.60%
Maturing 2042 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 1,107	1,107
Debt instrument, average interest rate percentage (as a percent)	4.00%
Maturing 2045 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 27	27
Debt instrument, average interest rate percentage (as a percent)	7.00%
Maturing 2046 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 650	650
Debt instrument, average interest rate percentage (as a percent)	4.70%
Maturing 2096 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 316	$ 316
Debt instrument, average interest rate percentage (as a percent)	7.13%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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