Assets and Liabilities Measured at Fair Value - Summary of Investments of Insurance Subsidiaries Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Money market funds and other	$ 301	$ 296
Investments of insurance subsidiaries	632	657
Less amounts classified as current assets	(101)	(88)
Asset fair value	531	569
Debt Securities [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities	331	361
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Money market funds and other	301	296
Investments of insurance subsidiaries	302	296
Less amounts classified as current assets	(101)	(88)
Asset fair value	201	208
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Debt Securities [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities	1
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments of insurance subsidiaries	330	361
Asset fair value	330	361
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities	$ 330	$ 361

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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+ Details

- Definition

Fair value of investment in security owned.

+ References

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+ Details

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References + Details

HCA Healthcare, Inc. 10-Q