Debt (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Senior Notes	Dec. 31, 2012 Senior Notes	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2014	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2014	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2015	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2015	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2015	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2015	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2017	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2017	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2018	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2018	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2019	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2019	Dec. 31, 2013 Senior Notes ACE INA senior notes due 2036	Dec. 31, 2012 Senior Notes ACE INA senior notes due 2036	Dec. 31, 2013 Senior secured debentures ACE INA debentures due 2029	Dec. 31, 2012 Senior secured debentures ACE INA debentures due 2029	Dec. 31, 2013 Trust Preferred Securities ACE INA capital securities due 2030	Mar. 31, 2000 Trust Preferred Securities ACE INA capital securities due 2030	Dec. 31, 2013 Reverse repurchase agreements	Dec. 31, 2012 Reverse repurchase agreements
Debt Instrument [Line Items]
Short-term debt	$ 1,901	$ 1,401			$ 500	$ 0																	$ 1,401	$ 1,401
Debt issued																					309	300
Long-term debt stated interest rate																					9.70%	9.70%
Current amount of long-term debt outstanding	3,807	3,360	3,807	3,360	0	500	449	449	700	699	500	500	300	300	500	500	299	299	100	100
ACE Capital Trust II common securities purchased																						$ 9.2