Borrowings - Long-Term Debt, Components (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Borrowings
Long-term debt, gross	$ 47,346	$ 43,196
Less: net unamortized discount	831	802
Less: net unamortized debt issuance cost	88	76
Add: fair value adjustment	406	337
Long-term debt (including current maturities)	46,833	42,656
Less: current maturities	7,106	7,051
Total long-term debt (excluding current portion)	39,727	35,605
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	$ 28,726	30,131
Euros
Borrowings
Long-term debt, gross	$ 15,438	10,011
Debt instrument, weighted-average interest rate (as a percent)	1.30%
Pound sterling
Borrowings
Long-term debt, gross	$ 1,368	1,338
Debt instrument, weighted-average interest rate (as a percent)	2.70%
Japanese yen
Borrowings
Long-term debt, gross	$ 1,314	1,325
Debt instrument, weighted-average interest rate (as a percent)	0.30%
Other
Borrowings
Long-term debt, gross	$ 500	391
Debt instrument, weighted-average interest rate (as a percent)	6.50%
Maturing 2019 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 3,959	5,465
Debt instrument, weighted-average interest rate (as a percent)	3.20%
Maturing 2020 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 4,338	4,344
Debt instrument, weighted-average interest rate (as a percent)	2.60%
Maturing 2021 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 5,531	5,529
Debt instrument, weighted-average interest rate (as a percent)	2.90%
Maturing 2022 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 3,529	3,536
Debt instrument, weighted-average interest rate (as a percent)	2.50%
Maturing 2023 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 2,413	2,428
Debt instrument, weighted-average interest rate (as a percent)	3.20%
Maturing 2024 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 2,046	2,037
Debt instrument, weighted-average interest rate (as a percent)	3.60%
Maturing 2025 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 600	600
Debt instrument, weighted-average interest rate (as a percent)	7.00%
Maturing 2026 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 1,350	1,350
Debt instrument, weighted-average interest rate (as a percent)	3.50%
Maturing 2027 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 969	969
Debt instrument, weighted-average interest rate (as a percent)	4.70%
Maturing 2028 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 313	313
Debt instrument, weighted-average interest rate (as a percent)	6.50%
Maturing 2030 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 149	32
Debt instrument, weighted-average interest rate (as a percent)	3.70%
Maturing 2032 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 600	600
Debt instrument, weighted-average interest rate (as a percent)	5.90%
Maturing 2038 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 83	83
Debt instrument, weighted-average interest rate (as a percent)	8.00%
Maturing 2039 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 745	745
Debt instrument, weighted-average interest rate (as a percent)	5.60%
Maturing 2042 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 1,107	1,107
Debt instrument, weighted-average interest rate (as a percent)	4.00%
Maturing 2045 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 27	27
Debt instrument, weighted-average interest rate (as a percent)	7.00%
Maturing 2046 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 650	650
Debt instrument, weighted-average interest rate (as a percent)	4.70%
Maturing 2096 \| U.S. dollars
Borrowings
Long-term debt, gross	$ 316	$ 316
Debt instrument, weighted-average interest rate (as a percent)	7.10%

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.

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