Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions		3 Months Ended	9 Months Ended
	Sep. 23, 2024 shares	Sep. 30, 2024 USD ($) Vote $ / shares shares	Sep. 30, 2024 USD ($) Vote $ / shares shares	Jul. 16, 2024 USD ($)	Jun. 30, 2024 shares	Jun. 18, 2024 USD ($)	Mar. 20, 2024 USD ($)	Dec. 31, 2023 $ / shares shares	Jul. 02, 2021 shares
Class Of Stock [Line Items]
Preferred stock, shares authorized		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 issued		0	0					0
Preferred stock, shares outstanding		0	0					0
Conversion ratio		1	1
Increase in equity | $			$ 273
Additional paid-in-capital deferred tax liabilities | $			18
Remaining authorized amount for future share repurchase program | $		$ 93	93
Accelerated Share Repurchase | Barclays Bank PLC
Class Of Stock [Line Items]
Common stock repurchase, authorized amount | $						$ 75
Accelerated share repurchase payments | $				$ 75
Percentage of shares equal to the settlement amount				0.80
Tax Receivable Agreement Liability
Class Of Stock [Line Items]
Additional TRA liabilities | $			$ 90
Class A Common Stock
Class Of Stock [Line Items]
Common stock, shares outstanding		532,444,353	532,444,353					510,900,000
Common shares, votes per share | Vote		1	1
Common stock, shares issued		559,500,000	559,500,000					517,300,000
Common stock, shares authorized		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
Conversion of noncontrolling interest (in shares)			28,937,401
Remaining authorized amount for future share repurchase program | $							$ 200
Number of shares repurchased			20,697,906
Class A Common Stock | Accelerated Share Repurchase
Class Of Stock [Line Items]
Accelerated share repurchase payments | $		$ 75	$ 75
Number of shares repurchased	2,400,041	10,563,306
Class B Common Stock
Class Of Stock [Line Items]
Common stock, shares outstanding		10,000,000.0	10,000,000.0					9,900,000
Issuance of common units (in shares)			14,999,998
Common stock, shares issued		10,000,000.0	10,000,000.0					9,900,000
Common stock, shares authorized		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		4,978,807	4,978,807
Common stock, shares issued		4,978,807	4,978,807
Common stock shares conversion ratio			1
Common stock shares convertible stock price trigger | $ / 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 | $ / shares			$ 12.50
Class B-2 Common Stock
Class Of Stock [Line Items]
Common stock, shares outstanding		4,978,807	4,978,807
Common stock, shares issued		4,978,807	4,978,807
Common stock shares conversion ratio			1
Common stock shares convertible stock price trigger | $ / 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 | $ / shares			$ 15.00
Class B-3 Common Stock
Class Of Stock [Line Items]
Common stock, shares outstanding		0	0
Common stock, shares issued		0	0
Common stock, shares authorized		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		560,433	560,433		554,568			28,962,218
Common shares, votes per share | Vote		1	1
Common stock, shares issued		600,000	600,000					29,000,000.0
Common stock shares conversion ratio			1
Common stock, shares authorized		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)			560,433
Conversion of noncontrolling interest (in shares)		(529,751)	(28,937,401)
Class Z Common Stock
Class Of Stock [Line Items]
Common stock, shares outstanding		0	0		578,097			3,420,215
Common stock, shares issued		0.0	0.0					3,400,000	8,671,507
Common stock, shares authorized		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		0	0
Class A Units
Class Of Stock [Line Items]
Common stock, shares outstanding		533,004,786	533,004,786
Held by non controlling interest			560,433
Alight Holdings | Class B-1 Common Units
Class Of Stock [Line Items]
Common stock, shares outstanding		2,521,192	2,521,192
Common stock, shares issued		2,521,192	2,521,192
Common stock shares conversion ratio			1
Common stock shares convertible stock price trigger | $ / 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 | $ / shares			$ 12.50
Alight Holdings | Class B-2 Common Units
Class Of Stock [Line Items]
Common stock, shares outstanding		2,521,192	2,521,192
Common stock, shares issued		2,521,192	2,521,192
Common stock shares conversion ratio			1
Common stock shares convertible stock price trigger | $ / 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 | $ / shares			$ 15.00