Investments (tables)

6 Months Ended

Jun. 30, 2017

Investments disclosure

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

	Amortized		Gross Unrealized				Fair
(at June 30, 2017, in millions)	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,023	$	10	$	5	$	2,028
Obligations of states, municipalities and political subdivisions:
Local general obligation	14,010		410		79		14,341
Revenue	11,589		317		63		11,843
State general obligation	1,612		45		11		1,646
Pre-refunded	4,112		172		—		4,284
Total obligations of states, municipalities and political subdivisions	31,323		944		153		32,114
Debt securities issued by foreign governments	1,537		24		5		1,556
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	1,675		97		5		1,767
All other corporate bonds	23,835		589		77		24,347
Redeemable preferred stock	89		6		—		95
Total	$	60,482	$	1,670	$	245	$	61,907

	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 June 30, 2017, in millions)	Cost		Gains		Losses		Value
Public common stock	$	443	$	130	$	6	$	567
Non-redeemable preferred stock	115		23		5		133
Total	$	558	$	153	$	11	$	700

			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 June 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	$	1,342	$	5	$	5	$	—	$	1,347	$	5
Obligations of states, municipalities and political subdivisions	6,088		142		179		11		6,267		153
Debt securities issued by foreign governments	432		5		—		—		432		5
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	470		5		37		—		507		5
All other corporate bonds	4,980		66		279		11		5,259		77
Total fixed maturities	13,312		223		500		22		13,812		245
Equity securities
Public common stock	150		3		14		3		164		6
Non-redeemable preferred stock	—		—		61		5		61		5
Total equity securities	150		3		75		8		225		11
Total	$	13,462	$	226	$	575	$	30	$	14,037	$	256

	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