Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Changes in:
Net unrealized gains (losses) on investments with other-than-temporary impairments	$ (14)	$ 39	$ 25	$ 81
Net unrealized gains (losses) on other investments	227	726	549	1,426
Net unrealized gains (losses) on investments	213	765	574	1,507
Net unrealized gains (losses) on discontinued operations and other		3	1	11
Foreign currency translation adjustment	(52)	37	(22)	44
Pension and postretirement benefits	1	2	3	5
Allocation to participating policyholders	(6)	(9)	(7)	(37)
Other comprehensive income (loss), net of tax	156	798	549	1,530
Net income (loss)	75	(125)	439	432
Comprehensive income (loss)	231	673	988	1,962
Changes in:
Net unrealized (gains) losses on investments attributable to noncontrolling interests		(13)	(8)	(27)
Pension and postretirement benefits attributable to noncontrolling interests				(3)
Other comprehensive (income) loss attributable to noncontrolling interests		13	8	30
Net (income) loss attributable to noncontrolling interests		(15)	(15)	(44)
Comprehensive (income) loss attributable to noncontrolling interests		28	23	74
Total comprehensive income (loss) attributable to CNA	$ 231	$ 645	$ 965	$ 1,888