Investments (tables)

12 Months Ended

Dec. 31, 2012

Investments disclosure

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

			Gross Unrealized
	Amortized Cost						Fair Value
(at December 31, 2012, in millions)			Gains		Losses
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,148	$	75	$	1	$	2,222
Obligations of states, municipalities and political subdivisions:
Pre-refunded		8,458		567		—		9,025
All other		27,405		2,262		11		29,656
Total obligations of states, municipalities and political subdivisions		35,863		2,829		11		38,681
Debt securities issued by foreign governments		2,185		72		—		2,257
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		2,744		255		2		2,997
All other corporate bonds		17,863		1,360		20		19,203
Redeemable preferred stock		26		7		—		33
Total	$	60,829	$	4,598	$	34	$	65,393

			Gross Unrealized
	Amortized Cost						Fair Value
(at December 31, 2011, in millions)			Gains		Losses
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	2,396	$	101	$	—	$	2,497
Obligations of states, municipalities and political subdivisions:
Pre-refunded		6,820		513		1		7,332
All other		29,391		2,303		4		31,690
Total obligations of states, municipalities and political subdivisions		36,211		2,816		5		39,022
Debt securities issued by foreign governments		2,228		91		1		2,318
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		3,288		249		22		3,515
All other corporate bonds		15,845		1,066		61		16,850
Redeemable preferred stock		26		4		—		30
Total	$	59,994	$	4,327	$	89	$	64,232

Amortized cost and fair value of fixed maturities by contractual maturity [Table Text Block]

(at December 31, 2012, in millions)	Amortized Cost		Fair Value
Due in one year or less	$	5,634	$	5,719
Due after 1 year through 5 years		21,498		22,944
Due after 5 years through 10 years		16,789		18,329
Due after 10 years		14,164		15,404
		58,085		62,396
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		2,744		2,997
Total	$	60,829	$	65,393

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

			Gross Unrealized
							Fair Value
(at December 31, 2012, in millions)	Cost		Gains		Losses
Common stock	$	366	$	148	$	4	$	510
Non-redeemable preferred stock		96		39		—		135
Total	$	462	$	187	$	4	$	645

			Gross Unrealized
							Fair Value
(at December 31, 2011, in millions)	Cost		Gains		Losses
Common stock	$	311	$	120	$	3	$	428
Non-redeemable preferred stock		103		29		1		131
Total	$	414	$	149	$	4	$	559

Unrealized investment losses [Table Text Block]

	Less than 12 months				12 months or longer				Total
(at December 31, 2012, 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	$	589	$	1	$	—	$	—	$	589	$	1
Obligations of states, municipalities and political subdivisions		611		9		45		2		656		11
Debt securities issued by foreign governments		186		—		2		—		188		—
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		70		—		36		2		106		2
All other corporate bonds		1,097		13		89		7		1,186		20
Total fixed maturities		2,553		23		172		11		2,725		34
Equity securities
Common stock		40		4		—		—		40		4
Non-redeemable preferred stock		13		—		—		—		13		—
Total equity securities		53		4		—		—		53		4
Total	$	2,606	$	27	$	172	$	11	$	2,778	$	38

	Less than 12 months				12 months or longer				Total
(at December 31, 2011, 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	$	356	$	—	$	—	$	—	$	356	$	—
Obligations of states, municipalities and political subdivisions		27		—		191		5		218		5
Debt securities issued by foreign governments		96		1		2		—		98		1
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		362		12		155		10		517		22
All other corporate bonds		1,295		42		105		19		1,400		61
Total fixed maturities		2,136		55		453		34		2,589		89
Equity securities
Common stock		64		3		—		—		64		3
Non-redeemable preferred stock		37		1		7		—		44		1
Total equity securities		101		4		7		—		108		4
Total	$	2,237	$	59	$	460	$	34	$	2,697	$	93

Securities continuously in an unrealized loss position of greater than 20% of amortized cost by length of time [Table Text Block]

	Period For Which Fair Value Is Less Than 80% of Amortized Cost
(in millions)	3 Months or Less		Greater Than 3 Months, 6 Months or Less		Greater Than 6 Months, 12 Months or Less		Greater Than 12 Months		Total
Fixed maturities:
Mortgage-backed securities	$	—	$	—	$	—	$	—	$	—
Other		—		1		—		3		4
Total fixed maturities		—		1		—		3		4
Equity securities		—		—		—		—		—
Total	$	—	$	1	$	—	$	3	$	4

Impairment charges included in net realized investment gains [Table Text Block]

(for the year ended December 31, in millions)	2012		2011		2010
Fixed maturities
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities	$	—	$	—	$	—
Obligations of states, municipalities and political subdivisions		—		—		—
Debt securities issued by foreign governments		—		—		—
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities		4		13		4
All other corporate bonds		4		5		9
Redeemable preferred stock		—		—		—
Total fixed maturities		8		18		13
Equity securities
Common stock		3		6		2
Non-redeemable preferred stock		1		—		1
Total equity securities		4		6		3
Other investments		3		1		10
Total	$	15	$	25	$	26

Roll-forward of the credit component of other-than-temporary impairments on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income [Table Text Block]

Year ended December 31, 2012 (in millions)	Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period		Additions for OTTI Securities Where No Credit Losses Were Previously Recognized		Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized		Reductions Due to Sales/Defaults of Credit- Impaired Securities			Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows		Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period
Fixed maturities
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	$	58	$	—	$	4	$	(1	)	$	2	$	63
All other corporate bonds		94		—		4		—			4		102
Total fixed maturities	$	152	$	—	$	8	$	(1	)	$	6	$	165

Year ended December 31, 2011 (in millions)	Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period		Additions for OTTI Securities Where No Credit Losses Were Previously Recognized		Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized		Reductions Due to Sales/Defaults of Credit- Impaired Securities			Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows			Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period
Fixed maturities
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities	$	47	$	—	$	12	$	—		$	(1	)	$	58
All other corporate bonds		88		2		2		(4	)		6			94
Total fixed maturities	$	135	$	2	$	14	$	(4	)	$	5		$	152

Net investment income [Table Text Block]

(for the year ended December 31, in millions)	2012		2011		2010
Gross investment income
Fixed maturities	$	2,439	$	2,543	$	2,710
Equity securities		28		29		31
Short-term securities		10		12		13
Real estate		34		34		35
Other investments		414		292		304
Gross investment income		2,925		2,910		3,093
Investment expenses		36		31		34
Net investment income	$	2,889	$	2,879	$	3,059

Changes in net unrealized investment gains [Table Text Block]

(at and for the year ended December 31, in millions)	2012			2011			2010
Changes in net unrealized investment gains
Fixed maturities	$	326		$	1,588		$	114
Equity securities		38			(2	)		69
Other investments		(2	)		(14	)		(178	)
		362			1,572			5
Related tax expense		130			560			2
Change in net unrealized gain on investment securities		232			1,012			3
Balance, beginning of year		2,871			1,859			1,856
Balance, end of year	$	3,103		$	2,871		$	1,859