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Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions |  |  | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 05, 2025 $ / shares | Jul. 02, 2021 shares | Sep. 30, 2025 USD ($) Vote series $ / shares shares | Jun. 30, 2025 $ / shares shares | Mar. 31, 2025 $ / shares | Sep. 30, 2024 USD ($) shares | Sep. 30, 2025 USD ($) Vote series $ / shares shares | Sep. 30, 2024 USD ($) shares | Feb. 13, 2025 USD ($) | Dec. 31, 2024 $ / shares shares | Jun. 30, 2024 shares | Dec. 31, 2023 shares
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 1,000,000 |  |  |  | 1,000,000 |  |  | 1,000,000.0 |  |
Preferred stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Preferred stock, shares outstanding (in shares) |  |  | 0 |  |  |  | 0 |  |  | 0 |  |
Preferred stock, shares issued (in shares) |  |  | 0 |  |  |  | 0 |  |  | 0 |  |
Conversion ratio |  |  | 1 |  |  |  | 1 |  |  |  |  |
Remaining authorized amount for future share repurchase program | $ |  |  | $ 216 |  |  |  | $ 216 |  |  |  |  |
Share repurchases | $ |  |  | $ 25 |  |  | $ 75 | $ 65 | $ 155 |  |  |  |
Treasury |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of shares repurchased (in shares) |  |  | 6,580,136 |  |  | 10,563,306 | 13,881,417 | 20,697,906 |  |  |  |
Share repurchases | $ |  |  | $ 25 |  |  | $ 75 | $ 65 | $ 155 |  |  |  |
Class A Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 522,640,188 |  |  |  | 522,640,188 |  |  | 531,700,000 |  |
Common shares, votes per share | Vote |  |  | 1 |  |  |  | 1 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 565,200,000 |  |  |  | 565,200,000 |  |  | 560,500,000 |  |
Common stock, shares authorized (in shares) |  |  | 1,000,000,000 |  |  |  | 1,000,000,000 |  |  | 1,000,000,000 |  |
Common stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Common stock repurchase, additional authorized amount | $ |  |  |  |  |  |  |  |  | $ 200 |  |  |
Common stock repurchase, authorized amount | $ |  |  |  |  |  |  |  |  | $ 281 |  |  |
Number of shares repurchased (in shares) |  |  | 6,580,136 |  |  |  | 13,881,417 |  |  |  |  |
Common stock dividends declared (in usd per share) | $ / shares |  |  | $ 0.04 | $ 0.04 | $ 0.04 |  |  |  |  |  |  |
Class A Common Stock | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock dividends declared (in usd per share) | $ / shares | $ 0.04 |  |  |  |  |  |  |  |  |  |  |
Class B Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 9,900,000 |  |  |  | 9,900,000 |  |  | 10,000,000.0 |  |
Issuance of common units (in shares) |  | 14,999,998 |  |  |  |  |  |  |  |  |  |
Number of common stock instruments | series |  |  | 2 |  |  |  | 2 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 9,900,000 |  |  |  | 9,900,000 |  |  | 10,000,000.0 |  |
Common stock, shares authorized (in shares) |  |  | 20,000,000.0 |  |  |  | 20,000,000.0 |  |  | 20,000,000.0 |  |
Common stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Class B-1 Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 4,955,297 |  |  |  | 4,955,297 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 4,955,297 |  |  |  | 4,955,297 |  |  |  |  |
Common stock shares conversion ratio |  |  |  |  |  |  | 1 |  |  |  |  |
Common stock shares convertible stock price trigger (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 12.50 |  |  |  |  |
Common stock shares convertible threshold trading days |  |  |  |  |  |  | 20 days |  |  |  |  |
Common stock shares convertible threshold consecutive trading days |  |  |  |  |  |  | 30 days |  |  |  |  |
Common stock shares convertible stock valuation price on diluted basis (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 12.50 |  |  |  |  |
Class B-1 Common Units | Alight Holdings |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 2,544,702 |  |  |  | 2,544,702 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 2,544,702 |  |  |  | 2,544,702 |  |  |  |  |
Common stock shares conversion ratio |  |  |  |  |  |  | 1 |  |  |  |  |
Common stock shares convertible stock price trigger (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 12.50 |  |  |  |  |
Common stock shares convertible threshold trading days |  |  |  |  |  |  | 20 days |  |  |  |  |
Common stock shares convertible threshold consecutive trading days |  |  |  |  |  |  | 30 days |  |  |  |  |
Common stock shares convertible stock valuation price on diluted basis (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 12.50 |  |  |  |  |
Class B-2 Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 4,955,297 |  |  |  | 4,955,297 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 4,955,297 |  |  |  | 4,955,297 |  |  |  |  |
Common stock shares conversion ratio |  |  |  |  |  |  | 1 |  |  |  |  |
Common stock shares convertible stock price trigger (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 15.00 |  |  |  |  |
Common stock shares convertible threshold trading days |  |  |  |  |  |  | 20 days |  |  |  |  |
Common stock shares convertible threshold consecutive trading days |  |  |  |  |  |  | 30 days |  |  |  |  |
Common stock shares convertible stock valuation price on diluted basis (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 15.00 |  |  |  |  |
Class B-2 Common Units | Alight Holdings |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 2,544,702 |  |  |  | 2,544,702 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 2,544,702 |  |  |  | 2,544,702 |  |  |  |  |
Common stock shares conversion ratio |  |  |  |  |  |  | 1 |  |  |  |  |
Common stock shares convertible stock price trigger (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 15.00 |  |  |  |  |
Common stock shares convertible threshold trading days |  |  |  |  |  |  | 20 days |  |  |  |  |
Common stock shares convertible threshold consecutive trading days |  |  |  |  |  |  | 30 days |  |  |  |  |
Common stock shares convertible stock valuation price on diluted basis (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 15.00 |  |  |  |  |
Class B-3 Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 0 |  |  |  | 0 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 0 |  |  |  | 0 |  |  |  |  |
Common stock, shares authorized (in shares) |  |  | 10,000,000 |  |  |  | 10,000,000 |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  |  |  |
Class V Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 510,115 | 510,115 |  | 560,433 | 510,115 | 560,433 |  | 510,237 | 554,568 | 28,962,218
Common shares, votes per share | Vote |  |  | 1 |  |  |  | 1 |  |  |  |  |
Common stock, shares issued (in shares) |  |  | 500,000 |  |  |  | 500,000 |  |  | 500,000 |  |
Common stock shares conversion ratio |  |  |  |  |  |  | 1 |  |  |  |  |
Common stock, shares authorized (in shares) |  |  | 175,000,000.0 |  |  |  | 175,000,000.0 |  |  | 175,000,000.0 |  |
Common stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Shares issued (in shares) |  |  |  |  |  |  | 510,115 |  |  |  |  |
Class Z Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 0 | 0 |  | 0 | 0 | 0 |  | 0 | 578,099 | 3,420,215
Common stock, shares issued (in shares) |  | 8,671,507 | 0.0 |  |  |  | 0.0 |  |  | 0.0 |  |
Common stock, shares authorized (in shares) |  |  | 12,900,000 |  |  |  | 12,900,000 |  |  | 12,900,000 |  |
Common stock, par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Class Z Common Units |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 0 |  |  |  | 0 |  |  |  |  |
Class A Units |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 523,150,303 |  |  |  | 523,150,303 |  |  |  |  |
Held by non controlling interest (in shares) |  |  |  |  |  |  | 510,115 |  |  |  |  |

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