Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Investments [Abstract]
Fixed maturities available for sale, at fair value (amortized cost - $48,384 and $47,826) (includes hybrid financial instruments of $284 and $274)	$ 50,410		$ 49,395
Fixed maturities held to maturity, at amortized cost (fair value – $7,307 and $7,589)	6,982		7,331
Equity securities, at fair value (cost – $447 and $440)	536		510
Short-term investments, at fair value and amortized cost	2,536		2,322
Other investments (cost – $3,096 and $2,999)	3,430		3,346
Total investments	63,894		62,904
Cash	948	[1],[2]	655	[1],[3]
Securities lending collateral	1,033		1,330
Accrued investment income	530		552
Insurance and reinsurance balances receivable	5,026		5,426
Reinsurance recoverable on losses and loss expenses	11,588		11,992
Reinsurance recoverable on policy benefits	215		217
Deferred policy acquisition costs	2,683		2,601
Value of business acquired	440		466
Goodwill and other intangible assets	5,516		5,724
Prepaid reinsurance premiums	1,981		2,026
Deferred tax assets	224		295
Investments in partially-owned insurance companies	590		504
Other assets	3,730		3,556
Total assets	98,398		98,248
Liabilities
Unpaid losses and loss expenses	37,326		38,315
Unearned premiums	8,182		8,222
Future policy benefits	4,744		4,754
Insurance and reinsurance balances payable	4,198		4,095
Securities lending payable	1,034		1,331
Accounts payable, accrued expenses, and other liabilities	6,194		5,726
Short-term debt	2,552		2,552
Long-term debt	4,157		3,357
Trust preferred securities	309		309
Total liabilities	68,696		68,661
Commitments and contingencies
Shareholders’ equity
Common Shares (CHF 24.15 and CHF 24.77 par value; 342,832,412 shares issued; 327,084,762 and 328,659,686 shares outstanding)	7,833		8,055
Common Shares in treasury (15,747,650 and 14,172,726 shares)	(1,645)		(1,448)
Additional paid-in capital	5,037		5,145
Retained earnings	17,325		16,644
Accumulated other comprehensive income (AOCI)	1,152		1,191
Total shareholders’ equity	29,702		29,587
Total liabilities and shareholders’ equity	$ 98,398		$ 98,248

[1] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At March 31, 2015 and December 31, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[2] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At March 31, 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At December 31, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.