Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule II. Condensed Financial Information of Registrant (Narrative)) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Aggregate amount of quantifiable indemnification agreements in effect for sales of business entities, assets and third party loans	$ 725
Recorded liabilities related to indemnification agreements	7	15
Parent Company [Member]
Percentage of CNAF common stock outstanding currently held by Loews	90.00%
Maximum exposure indebtedness of subsidiaries	10
Aggregate amount of quantifiable indemnification agreements in effect for sales of business entities, assets and third party loans	257
Recorded liabilities related to indemnification agreements
Maximum exposure SSAs	$ 1,900