| Financial Assets and Liabilities, Measured at Fair Value Recurring Basis [Table Text Block] |
The following table presents a summary of fair value measurements by level and carrying values for items measured at fair value on a recurring basis in the Condensed Consolidated Balance Sheets: | | | | | | | | | | | | | | | | | | | | | | | | | | | | (in millions) | | Quoted Prices
in Active
Markets
(Level 1) | | Other
Observable
Inputs
(Level 2) | | Unobservable
Inputs
(Level 3) | | Total
Fair and Carrying
Value | | March 31, 2026 | | | | | | | | | | Cash and cash equivalents | | $ | 21,576 | | $ | 6,425 | | $ | — | | $ | 28,001 | | Debt securities - available-for-sale: | | | | | | | | | | U.S. government and agency obligations | | 3,261 | | 176 | | — | | 3,437 | | State and municipal obligations | | — | | 5,779 | | — | | 5,779 | | Corporate obligations | | — | | 27,105 | | 433 | | 27,538 | | U.S. agency mortgage-backed securities | | — | | 10,275 | | — | | 10,275 | | Non-U.S. agency mortgage-backed securities | | — | | 3,077 | | — | | 3,077 | | Total debt securities - available-for-sale | | 3,261 | | 46,412 | | 433 | | 50,106 | | Equity securities | | 1,890 | | 22 | | 65 | | 1,977 | | Loan receivables | | — | | — | | 880 | | 880 | | Total assets at fair value | | $ | 26,727 | | $ | 52,859 | | $ | 1,378 | | $ | 80,964 | | Percentage of total assets at fair value | | 33 | % | | 65 | % | | 2 | % | | 100 | % | | December 31, 2025 | | | | | | | | | | Cash and cash equivalents | | $ | 19,848 | | $ | 4,517 | | $ | — | | $ | 24,365 | | Debt securities - available-for-sale: | | | | | | | | | | U.S. government and agency obligations | | 3,778 | | 154 | | — | | 3,932 | | State and municipal obligations | | — | | 6,325 | | — | | 6,325 | | Corporate obligations | | — | | 25,123 | | 423 | | 25,546 | | U.S. agency mortgage-backed securities | | — | | 9,719 | | — | | 9,719 | | Non-U.S. agency mortgage-backed securities | | — | | 2,660 | | — | | 2,660 | | Total debt securities - available-for-sale | | 3,778 | | 43,981 | | 423 | | 48,182 | | Equity securities | | 2,083 | | 20 | | 67 | | 2,170 | | Loan receivables | | — | | — | | 882 | | 882 | | Total assets at fair value | | $ | 25,709 | | $ | 48,518 | | $ | 1,372 | | $ | 75,599 | | Percentage of total assets at fair value | | 34 | % | | 64 | % | | 2 | % | | 100 | % |
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| Fair Value Measurements, Nonrecurring [Table Text Block] |
The following table presents a summary of fair value measurements by level and carrying values for certain financial instruments not measured at fair value on a recurring basis in the Condensed Consolidated Balance Sheets: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (in millions) | | Quoted Prices
in Active
Markets
(Level 1) | | Other
Observable
Inputs
(Level 2) | | Unobservable
Inputs
(Level 3) | | Total
Fair
Value | | Total Carrying Value | | March 31, 2026 | | | | | | | | | | | | Debt securities - held-to-maturity | | $ | 447 | | | $ | 24 | | | $ | — | | | $ | 471 | | | $ | 474 | | | Loan receivables | | — | | | 1,750 | | | 7,484 | | | 9,234 | | | 9,415 | | | Long-term debt and other financing obligations | | — | | | 69,323 | | | — | | | 69,323 | | | 74,537 | | | December 31, 2025 | | | | | | | | | | | | Debt securities - held-to-maturity | | $ | 463 | | | $ | 26 | | | $ | — | | | $ | 489 | | | $ | 490 | | | Loan receivables | | — | | | 1,700 | | | 6,923 | | | 8,623 | | | 8,860 | | | Long-term debt and other financing obligations | | — | | | 72,143 | | | — | | | 72,143 | | | 76,140 | |
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