Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2011

Comprehensive Income or Shareholders' Equity [Abstract]

Common stock activity

	Years Ended December 31
	2011			2010			2009
	(number of shares)
Common stock issued
Balance, beginning of year		371,980,460			371,980,460			371,980,710
Share activity under stock-based employee compensation plans		—			—			(250	)
Balance, end of year		371,980,460			371,980,460			371,980,460
Treasury stock
Balance, beginning of year		74,707,547			39,972,796			19,726,097
Repurchase of shares		27,582,889			37,667,829			22,623,775
Share activity under stock-based employee compensation plans		(2,770,927	)		(2,933,078	)		(2,377,076	)
Balance, end of year		99,519,509			74,707,547			39,972,796
Common stock outstanding, end of year		272,460,951			297,272,913			332,007,664

Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis

	December 31
	2011					2010
	GAAP			Statutory		GAAP			Statutory
	(in millions)
P&C Group	$	16,886		$	13,958	$	17,266		$	14,539
Corporate and other		(1,312	)				(1,736	)
	$	15,574				$	15,530

Comparison of GAAP and statutory net income (loss)

	Years Ended December 31
	2011					2010					2009
	GAAP			Statutory		GAAP			Statutory		GAAP			Statutory
	(in millions)
P&C Group	$	1,915		$	1,824	$	2,374		$	2,295	$	2,324		$	2,357
Corporate and other		(237	)				(200	)				(141	)
	$	1,678				$	2,174				$	2,183