The value of the shares of ACE Capital Trust II purchased by ACE INA.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Debt (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
Debt (Narrative) (Details) - USD ($) $ in Millions	Jan. 14, 2016	Dec. 31, 2017	Apr. 14, 2017	Mar. 31, 2000
Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Debt issued		$ 1,000.0
Junior Subordinated Debt [Member] \| Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Long-term debt stated interest rate		3.97%	6.375%
Debt issued		$ 1,000.0
Junior Subordinated Debt [Member] \| Chubb INA Capital Securities Due 2067 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%
Senior Notes [Member] \| INA Senior Notes Due February 2017 [Member]
Debt Instrument [Line Items]
Long-term debt stated interest rate		5.70%
Debt issued		$ 500.0
Trust Preferred Securities \| INA capital securities due 2030
Debt Instrument [Line Items]
Long-term debt stated interest rate		9.70%		9.70%
Debt issued		$ 309.0		$ 300.0
ACE Capital Trust II common securities purchased				$ 9.2
The Chubb Corporation [Member]
Debt Instrument [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred	$ 5,300.0