Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 29, 2011
Percentage owned of outstanding common stock by majority shareholder	90.00%
Business Acquisition, Purchase Price		$ 231,000,000
Business Combination, Acquisition Related Costs		4,000,000
Sale of CNA ownership percentage of FICOH				50.00%
Anticipated amounts due from insureds related to losses under deductible policies	1,300,000,000	1,300,000,000
Minimum interest rate used in determining present value of obligations of structured settlements not funded by annuities	7.10%	7.10%
Maximum interest rate used in determining present value of obligations of structured settlements not funded by annuities	9.70%	9.70%
Discounted reserves for unfunded structured settlements	580,000,000	602,000,000
Discounted reserves for unfunded structure settlements, discount amount	969,000,000	1,000,000,000
Minimum interest rate used to discount workers' compensation lifetime claim reserves and accident and health claim reserves	3.00%	3.00%
Maximum interest rate used to discount workers' compensation lifetime claim reserves and accident and health claim reserves	6.80%	6.50%
Discounted reserves for worker's compensation lifetime claim reserves and accident and health claim reserves	2,400,000,000	2,200,000,000
Discounted reserves for worker's compensation lifetime claim reserves and accident and health claim reserves, discount amount	617,000,000	837,000,000
Minimum interest rate used to calculate reserves for long term care products	4.50%	5.00%
Maximum interest rate used to calculate reserves for payout annuity contracts	7.90%	7.40%
Minimum interest rate used to calculate reserves for payout annuity contracts	5.00%	5.00%
Maximum interest rate used to calculate reserves for payout annuity contracts	8.70%	8.70%
Increase in insurance reserves due to unlocking actuarial assumptions related to payout annuity contracts		33,000,000
Liability balance for guaranty fund	143,000,000	143,000,000
Related assets for premium tax offsets included in other assets	1,000,000	2,000,000
Percentage of billed receivables compared to total reinsurance receivables	5% or less
Deposit assets	3,000,000	3,000,000
Deposit liabilities	130,000,000	125,000,000
Deferred acquisition costs, net of shadow adjustment	342,000,000	369,000,000
Investments in life settlement contracts	88,000,000	100,000,000
Increase (decrease) in fair value recognized on life settlement contracts	(2,000,000)	11,000,000	5,000,000
Gain recognized on matured life settlement contracts	15,000,000	42,000,000	28,000,000
Decrease in shadow adjustment, net of tax	979,000,000
Increase in shadow adjustment, net of tax		789,000,000
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	532,000,000	1,511,000,000
Foreign currency transaction gain (loss), before tax	2,000,000	12,000,000	4,000,000
Weighted average number diluted shares outstanding adjustment	552,000	417,000	290,000
Antidilutive securities excluded from computation of earnings per share, amount	111,000	730,000	1,100,000
Interest paid, net	164,000,000	170,000,000	175,000,000
Proceeds from income tax refunds		29,000,000
Income taxes paid	$ 129,000,000		$ 61,000,000
Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	7 years
Office Equipment [Member]
Property, Plant and Equipment, Useful Life	5 years
Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	50 years
Minimum [Member]
Requisite service period for stock- based compensation expense	3 years
Minimum [Member] | Software [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Requisite service period for stock- based compensation expense	4 years
Maximum [Member] | Software [Member]
Property, Plant and Equipment, Useful Life	5 years
Property and Casualty insurance core operations [Member]
Number of Operating Segments	3
Life and Group Non-Core & Corporate and Other Non-Core operations [Member]
Number of Operating Segments	2