Investments (tables)

9 Months Ended

Sep. 30, 2016

Investments disclosure

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

	Amortized		Gross Unrealized				Fair
(at September 30, 2016, in millions)	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,046	$	27	$	2	$	2,071
Obligations of states, municipalities and political subdivisions:
Local general obligation	13,930		754		9		14,675
Revenue	10,668		608		6		11,270
State general obligation	1,878		95		3		1,970
Pre-refunded	5,138		227		—		5,365
Total obligations of states, municipalities and political subdivisions	31,614		1,684		18		33,280
Debt securities issued by foreign governments	1,703		54		—		1,757
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	1,651		128		1		1,778
All other corporate bonds	23,039		1,039		31		24,047
Redeemable preferred stock	96		7		—		103
Total	$	60,149	$	2,939	$	52	$	63,036

	Amortized		Gross Unrealized				Fair
(at December 31, 2015, in millions)	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,202	$	8	$	16	$	2,194
Obligations of states, municipalities and political subdivisions:
Local general obligation	12,744		577		3		13,318
Revenue	9,492		472		4		9,960
State general obligation	1,978		97		2		2,073
Pre-refunded	5,813		247		—		6,060
Total obligations of states, municipalities and political subdivisions	30,027		1,393		9		31,411
Debt securities issued by foreign governments	1,829		45		1		1,873
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	1,863		124		6		1,981
All other corporate bonds	22,854		523		288		23,089
Redeemable preferred stock	103		7		—		110
Total	$	58,878	$	2,100	$	320	$	60,658

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

			Gross Unrealized				Fair
(at September 30, 2016, in millions)	Cost		Gains		Losses		Value
Public common stock	$	394	$	218	$	3	$	609
Non-redeemable preferred stock	116		24		5		135
Total	$	510	$	242	$	8	$	744

			Gross Unrealized				Fair
(at December 31, 2015, in millions)	Cost		Gains		Losses		Value
Public common stock	$	386	$	164	$	7	$	543
Non-redeemable preferred stock	142		26		6		162
Total	$	528	$	190	$	13	$	705

Unrealized investment losses [Table Text Block]

	Less than 12 months				12 months or longer				Total
(at September 30, 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	$	146	$	1	$	10	$	1	$	156	$	2
Obligations of states, municipalities and political subdivisions	2,255		18		14		—		2,269		18
Debt securities issued by foreign governments	31		—		—		—		31		—
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	116		—		20		1		136		1
All other corporate bonds	1,002		7		502		24		1,504		31
Redeemable preferred stock	—		—		7		—		7		—
Total fixed maturities	3,550		26		553		26		4,103		52
Equity securities
Public common stock	9		1		20		2		29		3
Non-redeemable preferred stock	5		—		60		5		65		5
Total equity securities	14		1		80		7		94		8
Total	$	3,564	$	27	$	633	$	33	$	4,197	$	60

	Less than 12 months				12 months or longer				Total
(at December 31, 2015, 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	$	1,820	$	15	$	28	$	1	$	1,848	$	16
Obligations of states, municipalities and political subdivisions	928		7		142		2		1,070		9
Debt securities issued by foreign governments	172		1		—		—		172		1
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	473		4		57		2		530		6
All other corporate bonds	7,725		197		710		91		8,435		288
Redeemable preferred stock	8		—		—		—		8		—
Total fixed maturities	11,126		224		937		96		12,063		320
Equity securities
Public common stock	48		6		33		1		81		7
Non-redeemable preferred stock	47		3		38		3		85		6
Total equity securities	95		9		71		4		166		13
Total	$	11,221	$	233	$	1,008	$	100	$	12,229	$	333