Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Level within the fair value hierarchy at which the Company's financial assets and financial liabilities reported at fair value are measured on a recurring basis [Table Text Block]

The following tables present the level within the fair value hierarchy at which the Company’s financial assets and financial liabilities are measured on a recurring basis.   

(at September 30, 2020, in millions)	Total		Level 1		Level 2		Level 3
Invested assets:
Fixed maturities
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,126	$	2,126	$	—	$	—
Obligations of states, municipalities and political subdivisions	34,841		—		34,830		11
Debt securities issued by foreign governments	979		—		979		—
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	2,730		—		2,730		—
All other corporate bonds	31,874		6		31,787		81
Redeemable preferred stock	24		—		24		—
Total fixed maturities	72,574		2,132		70,350		92
Equity securities
Public common stock	368		368		—		—
Non-redeemable preferred stock	42		21		21		—
Total equity securities	410		389		21		—
Other investments	48		14		—		34
Total	$	73,032	$	2,535	$	70,371	$	126
Other liabilities	$	7	$	—	$	—	$	7

(at December 31, 2019, in millions)	Total		Level 1		Level 2		Level 3
Invested assets:
Fixed maturities
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,095	$	2,095	$	—	$	—
Obligations of states, municipalities and political subdivisions	29,917		—		29,905		12
Debt securities issued by foreign governments	1,173		—		1,173		—
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	3,280		—		3,280		—
All other corporate bonds	31,619		—		31,530		89
Redeemable preferred stock	50		—		50		—
Total fixed maturities	68,134		2,095		65,938		101
Equity securities
Public common stock	383		383		—		—
Non-redeemable preferred stock	42		13		29		—
Total equity securities	425		396		29		—
Other investments	36		16		—		20
Total	$	68,595	$	2,507	$	65,967	$	121
Other liabilities	$	8	$	—	$	—	$	8

Carrying value and fair value of financial instruments disclosed, but not carried, at fair value and the level within the fair value hierarchy at which such financial instruments are categorized [Table Text Block]

The following tables present the carrying value and fair value of the Company’s financial assets and financial liabilities disclosed, but not carried, at fair value, and the level within the fair value hierarchy at which such assets and liabilities are categorized.

(at September 30, 2020, in millions)	Carrying Value		Fair Value		Level 1		Level 2		Level 3
Financial assets
Short-term securities	$	6,329	$	6,329	$	977	$	5,307	$	45
Financial liabilities
Debt	$	6,950	$	9,083	$	—	$	9,083	$	—
Commercial paper	$	100	$	100	$	—	$	100	$	—

(at December 31, 2019, in millions)	Carrying Value		Fair Value		Level 1		Level 2		Level 3
Financial assets
Short-term securities	$	4,943	$	4,943	$	685	$	4,204	$	54
Financial liabilities
Debt	$	6,458	$	8,049	$	—	$	8,049	$	—
Commercial paper	$	100	$	100	$	—	$	100	$	—