Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Net earned premiums	$ 6,603	$ 6,515	$ 6,721
Net investment income	2,054	2,316	2,320
Net realized investment gains (losses), net of participating policyholders’ interests:
Other-than-temporary impairment losses	(175)	(254)	(1,657)
Portion of other-than-temporary impairments recognized in Other comprehensive income (loss)	(41)	22	305
Net other-than-temporary impairment losses recognized in earnings	(216)	(232)	(1,352)
Other net realized investment gains (losses)	212	318	495
Net realized investment gains (losses), net of participating policyholders’ interests	(4)	86	(857)
Other revenues	294	292	288
Total revenues	8,947	9,209	8,472
Claims, Benefits and Expenses
Insurance claims and policyholders’ benefits	5,489	4,985	5,290
Amortization of deferred acquisition costs	1,410	1,387	1,417
Other operating expenses	996	1,568	1,097
Interest	175	157	128
Total claims, benefits and expenses	8,070	8,097	7,932
Income (loss) from continuing operations before income tax	877	1,112	540
Income tax (expense) benefit	(246)	(333)	(57)
Income (loss) from continuing operations, net of tax	631	779	483
Income (loss) from discontinued operations, net of income tax (expense) benefit of $0, $0 and $0	(1)	(21)	(2)
Net income (loss)	630	758	481
Net (income) loss attributable to noncontrolling interests	(16)	(68)	(62)
Net income (loss) attributable to CNA	614	690	419
Income (Loss) Attributable to Common Stockholders
Income (loss) from continuing operations attributable to CNA	615	711	421
Dividends on 2008 Senior Preferred		(76)	(122)
Income (loss) from continuing operations attributable to CNA common stockholders	615	635	299
Income (loss) from discontinued operations attributable to CNA common stockholders	(1)	(21)	(2)
Income (loss) attributable to CNA common stockholders	$ 614	$ 614	$ 297
Basic and Diluted Earnings (Loss) Per Share Attributable to CNA Common Stockholders
Income (loss) from continuing operations attributable to CNA common stockholders	$ 2.28	$ 2.36	$ 1.11
Income (loss) from discontinued operations attributable to CNA common stockholders		$ (0.08)	$ (0.01)
Basic and diluted earnings (loss) per share attributable to CNA common stockholders	$ 2.28	$ 2.28	$ 1.10
Weighted Average Outstanding Common Stock and Common Stock Equivalents
Basic	269.3	269.1	269.0
Diluted	269.6	269.5	269.1