Fair Values of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2011

Fair Values of Financial Instruments (Tables) [Abstract]

Carrying values and fair values of financial instruments

	June 30, 2011				December 31, 2010
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
	(in millions)
Assets
Invested assets
Short term investments	$	1,690	$	1,690	$	1,905	$	1,905
Fixed maturities		37,367		37,367		36,519		36,519
Equity securities		1,663		1,663		1,550		1,550
Liabilities
Long term debt		3,975		4,262		3,975		4,318

Fair values of fixed maturities and equity securities categorized based upon the lowest level of input

	June 30, 2011
	Level 1		Level 2		Level 3		Total
	(in millions)
Fixed maturities
Tax exempt	$	—	$	20,156	$	8	$	20,164
Taxable
U.S. Government and government agency and authority obligations		—		832		—		832
Corporate bonds		—		6,666		189		6,855
Foreign government and government agency obligations		—		6,516		6		6,522
Residential mortgage-backed securities		—		1,092		16		1,108
Commercial mortgage-backed securities		—		1,886		—		1,886
		—		16,992		211		17,203
Total fixed maturities		—		37,148		219		37,367
Equity securities		1,655		—		8		1,663
	$	1,655	$	37,148	$	227	$	39,030

	December 31, 2010
	Level 1		Level 2		Level 3		Total
	(in millions)
Fixed maturities
Tax exempt	$	—	$	19,765	$	9	$	19,774
Taxable
U.S. Government and government agency and authority obligations		—		829		—		829
Corporate bonds		—		6,483		165		6,648
Foreign government and government agency obligations		—		6,135		26		6,161
Residential mortgage-backed securities		—		1,329		21		1,350
Commercial mortgage-backed securities		—		1,757		—		1,757
		—		16,533		212		16,745
Total fixed maturities		—		36,298		221		36,519
Equity securities		1,537		—		13		1,550
	$	1,537	$	36,298	$	234	$	38,069