Investments - Summary of Investments (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,735	$ 3,208
Gross unrealized gains	2	12
Gross unrealized losses	170	18
Estimated Fair Value	3,567	3,202
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,372	1,836
Gross unrealized gains	2	9
Gross unrealized losses	106	12
Estimated Fair Value	2,268	1,833
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	759	616
Gross unrealized gains	0	2
Gross unrealized losses	42	4
Estimated Fair Value	717	614
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	306	248
Gross unrealized gains	0	0
Gross unrealized losses	13	1
Estimated Fair Value	293	247
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	153	123
Gross unrealized gains	0	1
Gross unrealized losses	7	1
Estimated Fair Value	146	123
U.S. Treasury notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	96	353
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated Fair Value	96	353
Other
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	49	32
Gross unrealized gains	0	0
Gross unrealized losses	2	0
Estimated Fair Value	$ 47	$ 32

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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Amortized cost excluding accrued interest, after allowance for credit loss, 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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
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-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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