Investments (Details) - Investment Information, Debt Securities - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Investment disclosure details
Fixed maturities, amortized cost	$ 76,158		$ 74,751
Allowance for expected credit losses	4		3
Gross unrealized gains	846		3,356
Gross unrealized losses	2,614		294
Fixed maturities, at fair value	74,386		77,810
Proceeds from sales of fixed maturities classified as available for sale	1,044	$ 1,238
Gross realized gains	5	15
Gross realized losses	2	1
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	3,356		3,574
Allowance for expected credit losses	0		0
Gross unrealized gains	7		20
Gross unrealized losses	190		32
Fixed maturities, at fair value	3,173		3,562
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	35,992		34,925
Allowance for expected credit losses	0		0
Gross unrealized gains	559		2,012
Gross unrealized losses	1,263		75
Fixed maturities, at fair value	35,288		36,862
Obligations of U.S. states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	19,345		18,668
Allowance for expected credit losses	0		0
Gross unrealized gains	275		1,045
Gross unrealized losses	821		46
Fixed maturities, at fair value	18,799		19,667
Obligations of U.S. states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	11,585		11,274
Allowance for expected credit losses	0		0
Gross unrealized gains	172		693
Gross unrealized losses	396		27
Fixed maturities, at fair value	11,361		11,940
Obligations of U.S. states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,180		1,158
Allowance for expected credit losses	0		0
Gross unrealized gains	19		67
Gross unrealized losses	46		2
Fixed maturities, at fair value	1,153		1,223
Obligations of U.S. states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	3,882		3,825
Allowance for expected credit losses	0		0
Gross unrealized gains	93		207
Gross unrealized losses	0		0
Fixed maturities, at fair value	3,975		4,032
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,073		1,041
Allowance for expected credit losses	0		0
Gross unrealized gains	0		7
Gross unrealized losses	32		7
Fixed maturities, at fair value	1,041		1,041
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,791		1,754
Allowance for expected credit losses	0		0
Gross unrealized gains	23		68
Gross unrealized losses	54		5
Fixed maturities, at fair value	1,760		1,817
Corporate and all other bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	33,946		33,457
Allowance for expected credit losses	4	$ 2	3	$ 2
Gross unrealized gains	257		1,249
Gross unrealized losses	1,075		175
Fixed maturities, at fair value	$ 33,124		$ 34,528

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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