Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2015		Dec. 31, 2014
Investments [Abstract]
Fixed maturities available for sale, at fair value (amortized cost - $47,599 and $47,826) (includes hybrid financial instruments of $282 and $274)		$ 48,701		$ 49,395
Fixed maturities held to maturity, at amortized cost (fair value – $8,805 and $7,589)		8,676		7,331
Equity securities, at fair value (cost – $433 and $440)		498		510
Short-term investments, at fair value and amortized cost		2,062		2,322
Other investments (cost – $2,989 and $2,999)		3,328		3,346
Total investments		63,265		62,904
Cash	[1]	790	[2]	655	[3]
Securities lending collateral		1,080		1,330
Accrued investment income		534		552
Insurance and reinsurance balances receivable		5,757		5,426
Reinsurance recoverable on losses and loss expenses		11,775		11,992
Reinsurance recoverable on policy benefits		203		217
Deferred policy acquisition costs		2,806		2,601
Value of business acquired		434		466
Goodwill and other intangible assets		5,969		5,724
Prepaid reinsurance premiums		2,238		2,026
Deferred tax assets		285		295
Investments in partially-owned insurance companies		638		504
Other assets		4,066		3,556
Total assets		99,840		98,248
Liabilities
Unpaid losses and loss expenses		38,230		38,315
Unearned premiums		8,879		8,222
Future policy benefits		4,835		4,754
Insurance and reinsurance balances payable		4,602		4,095
Securities lending payable		1,081		1,331
Accounts payable, accrued expenses, and other liabilities		6,090		5,726
Short-term debt		2,102		2,552
Long-term debt		4,157		3,357
Trust preferred securities		309		309
Total liabilities		$ 70,285		$ 68,661
Commitments and contingencies
Shareholders’ equity
Common Shares (CHF 24.15 and CHF 24.77 par value; 342,832,412 shares issued; 323,814,281 and 328,659,686 shares outstanding)		$ 7,833		$ 8,055
Common Shares in treasury (19,018,131 and 14,172,726 shares)		(1,999)		(1,448)
Additional paid-in capital		4,847		5,145
Retained earnings		18,267		16,644
Accumulated other comprehensive income (AOCI)		607		1,191
Total shareholders’ equity		29,555		29,587
Total liabilities and shareholders’ equity		$ 99,840		$ 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 June 30, 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 June 30, 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.