Investments (tables)

9 Months Ended

Sep. 30, 2017

Investments disclosure

Amortized cost and fair value of investments in fixed maturities [Table Text Block]

	Amortized		Gross Unrealized				Fair
(at September 30, 2017, in millions)	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,064	$	9	$	5	$	2,068
Obligations of states, municipalities and political subdivisions:
Local general obligation	13,798		410		67		14,141
Revenue	11,341		324		51		11,614
State general obligation	1,555		45		9		1,591
Pre-refunded	3,666		163		—		3,829
Total obligations of states, municipalities and political subdivisions	30,360		942		127		31,175
Debt securities issued by foreign governments	1,559		17		11		1,565
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	2,082		97		6		2,173
All other corporate bonds	24,572		587		79		25,080
Redeemable preferred stock	90		6		—		96
Total	$	60,727	$	1,658	$	228	$	62,157

	Amortized		Gross Unrealized				Fair
(at December 31, 2016, in millions)	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,031	$	9	$	5	$	2,035
Obligations of states, municipalities and political subdivisions:
Local general obligation	13,955		271		182		14,044
Revenue	10,910		215		147		10,978
State general obligation	1,717		36		22		1,731
Pre-refunded	4,968		190		1		5,157
Total obligations of states, municipalities and political subdivisions	31,550		712		352		31,910
Debt securities issued by foreign governments	1,631		34		3		1,662
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	1,614		100		6		1,708
All other corporate bonds	22,737		508		138		23,107
Redeemable preferred stock	87		6		—		93
Total	$	59,650	$	1,369	$	504	$	60,515

Cost and fair value of investments in equity securities [Table Text Block]

			Gross Unrealized				Fair
(at September 30, 2017, in millions)	Cost		Gains		Losses		Value
Public common stock	$	392	$	80	$	2	$	470
Non-redeemable preferred stock	117		20		6		131
Total	$	509	$	100	$	8	$	601

			Gross Unrealized				Fair
(at December 31, 2016, in millions)	Cost		Gains		Losses		Value
Public common stock	$	390	$	216	$	3	$	603
Non-redeemable preferred stock	114		20		5		129
Total	$	504	$	236	$	8	$	732

Unrealized investment losses [Table Text Block]

	Less than 12 months				12 months or longer				Total
(at September 30, 2017, in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Fixed maturities
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	1,348	$	4	$	72	$	1	$	1,420	$	5
Obligations of states, municipalities and political subdivisions	4,131		58		1,598		69		5,729		127
Debt securities issued by foreign governments	538		11		—		—		538		11
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	729		5		81		1		810		6
All other corporate bonds	4,896		57		679		22		5,575		79
Total fixed maturities	11,642		135		2,430		93		14,072		228
Equity securities
Public common stock	39		1		6		1		45		2
Non-redeemable preferred stock	—		—		60		6		60		6
Total equity securities	39		1		66		7		105		8
Total	$	11,681	$	136	$	2,496	$	100	$	14,177	$	236

	Less than 12 months				12 months or longer				Total
(at December 31, 2016, in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Fixed maturities
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	1,124	$	5	$	—	$	—	$	1,124	$	5
Obligations of states, municipalities and political subdivisions	9,781		352		12		—		9,793		352
Debt securities issued by foreign governments	360		3		—		—		360		3
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	528		5		43		1		571		6
All other corporate bonds	6,470		115		437		23		6,907		138
Total fixed maturities	18,263		480		492		24		18,755		504
Equity securities
Public common stock	45		2		10		1		55		3
Non-redeemable preferred stock	2		—		59		5		61		5
Total equity securities	47		2		69		6		116		8
Total	$	18,310	$	482	$	561	$	30	$	18,871	$	512