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Long-Term Debt - Narrative (Details) - USD ($) |  |  | 12 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 28, 2018 | Sep. 29, 2015 | Dec. 31, 2019 | Feb. 06, 2020 | Sep. 11, 2019 | Mar. 13, 2019 | Feb. 01, 2019 | Oct. 29, 2018 | Jun. 13, 2018 | Apr. 30, 2018 | Mar. 07, 2018
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Bank note, maximum issuable amount | $ 20,000,000,000 | $ 20,000,000,000 |  |  |  |  |  |  |  |  |
Senior notes available for future issuance |  |  | $ 18,700,000,000 |  |  |  |  |  |  |  |
Senior Notes [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Original maturity of bank note | 7 days | 7 days |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  | $ 1,400,000,000 |  |  |  |  |  |  |  |
Subordinated Notes [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Original maturity of bank note | 5 years | 5 years |  |  |  |  |  |  |  |  |
3.375% Senior Notes Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  |  |  |  |  | $ 500,000,000
Debt instrument interest rate |  |  |  |  |  |  |  |  |  |  | 3.375%
3.35% Senior Notes Due 2021 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  |  |  | $ 500,000,000 |  |
Debt instrument interest rate |  |  |  |  |  |  |  |  | 3.35% |  |
3.300% Senior Notes Due 2022 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  | $ 600,000,000 |  |  |  |
Debt instrument interest rate |  |  |  |  |  |  | 3.30% |  |  |  |
Floating Rate Senior Notes Due 2022 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  | $ 400,000,000 |  |  |  |
3.900% Subordinated Notes Due 2029 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  | $ 350,000,000 |  |  |  |  |
Debt instrument interest rate |  |  |  |  |  | 3.90% |  |  |  |  |
Medium-Term Notes [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Debt term |  |  | 9 months |  |  |  |  |  |  |  |
Additional debt securities authorized and available for issuance under note program |  |  | $ 2,000,000,000.0 |  |  |  |  |  |  |  |
4.10% Senior Notes Due 2028 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  |  |  |  | $ 750,000,000 |
Debt instrument interest rate |  |  |  |  |  |  |  |  |  | 4.10% |
4.150% Senior Notes Due 2025 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  |  |  |  | $ 500,000,000 |  |  |
Debt instrument interest rate |  |  |  |  |  |  |  | 4.15% |  |  |
2.550% Senior Notes Due 2029 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  |  | $ 750,000,000 |  |  |  |  |  |
Debt instrument interest rate |  |  |  |  | 2.55% |  |  |  |  |  |
Subsequent Event [Member] | 2.250% Senior Notes Due 2027 [Member] |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of senior notes |  |  |  | $ 800,000,000 |  |  |  |  |  |  |
Debt instrument interest rate |  |  |  | 2.25% |  |  |  |  |  |  |

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- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16(a)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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