Short-term and Long-term Investments, Restricted Deposits - By Investment Type (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities
Gross Unrealized Gains	$ 54	$ 20
Gross Unrealized Losses	(1,142)	(1,364)
Equity securities	250	5
Private equity investments	540	529
Life insurance contracts	176	169
Total, Amortized Cost	20,369	19,566
Total, Fair Value	19,281	18,222
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Debt Securities
Amortized Cost	489	695
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12)	(16)
Fair Value	477	679
Corporate securities
Debt Securities
Amortized Cost	10,523	10,127
Gross Unrealized Gains	32	12
Gross Unrealized Losses	(668)	(778)
Fair Value	9,887	9,361
Restricted certificates of deposit
Debt Securities
Amortized Cost	4	4
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	4	4
Restricted cash equivalents
Debt Securities
Amortized Cost	312	256
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	312	256
Short-term time deposits
Debt Securities
Amortized Cost	198	204
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	198	204
Municipal securities
Debt Securities
Amortized Cost	4,131	4,055
Gross Unrealized Gains	15	6
Gross Unrealized Losses	(213)	(280)
Fair Value	3,933	3,781
Asset-backed securities
Debt Securities
Amortized Cost	1,492	1,396
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(57)	(70)
Fair Value	1,437	1,326
Residential mortgage-backed securities
Debt Securities
Amortized Cost	1,187	1,165
Gross Unrealized Gains	4	2
Gross Unrealized Losses	(105)	(121)
Fair Value	1,086	1,046
Commercial mortgage-backed securities
Debt Securities
Amortized Cost	1,067	961
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(87)	(99)
Fair Value	$ 981	$ 862

Investments, Debt Securities, Equity Method Investments And Other, Amortized Cost

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Investments, Debt Securities, Equity Securities And Other, Fair Value

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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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Amount excluding accrued interest, 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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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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