Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule II. Condensed Financial Information of Registrant (Narrative)) (Details) (USD $)	12 Months Ended		12 Months Ended			11 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Parent Company [Member]	Dec. 31, 2010 Parent Company [Member]	Feb. 01, 2011 Senior notes 5.750%, face amount $400, due August 15, 2021 [Member]	Dec. 31, 2011 Extinguished senior notes, due August 15, 2011 [Member]	Feb. 01, 2011 Extinguished senior notes, due August 15, 2011 [Member]
Percentage of CNAF common stock outstanding currently held by Loews			90.00%
Senior notes issued					$ 400,000,000
Stated interest rate on senior notes					5.75%		6.00%
Redemption of debt						400,000,000
Line of credit facility, initiation date	August 1, 2007
Line of credit facility, expiration date	August 1, 2012
Maximum borrowing capacity under revolving credit facilities	250,000,000
Debt instrument, description of variable rate basis	London Interbank Offered Rate (LIBOR) plus the Company's credit risk spread		London Interbank Offered Rate (LIBOR) plus CNAF’s credit risk spread
Limit available for credit agreement	250,000,000
Maximum exposure indebtedness of subsidiaries			10,000,000
Aggregate amount of quantifiable indemnification agreements in effect for sales of business entities, assets and third party loans	764,000,000		258,000,000
Recorded liabilities related to indemnification agreements	15,000,000	16,000,000	8,000,000	9,000,000
Maximum exposure SSAs			$ 1,900,000,000