Consolidated Balance Sheets - USD ($) $ in Millions		Sep. 30, 2015		Dec. 31, 2014
Investments [Abstract]
Fixed maturities available for sale, at fair value (amortized cost - $47,411 and $47,826) (includes hybrid financial instruments of $217 and $274)		$ 48,278		$ 49,395
Fixed maturities held to maturity, at amortized cost (fair value – $8,750 and $7,589)		8,564		7,331
Equity securities, at fair value (cost – $434 and $440)		464		510
Short-term investments, at fair value and amortized cost		1,808		2,322
Other investments (cost – $2,943 and $2,999)		3,270		3,346
Total investments		62,384		62,904
Cash	[1]	1,038	[2]	655	[3]
Securities lending collateral		1,011		1,330
Accrued investment income		530		552
Insurance and reinsurance balances receivable		5,290		5,426
Reinsurance recoverable on losses and loss expenses		11,231		11,992
Reinsurance recoverable on policy benefits		194		217
Deferred policy acquisition costs		2,809		2,601
Value of business acquired		410		466
Goodwill and other intangible assets		5,713		5,724
Prepaid reinsurance premiums		2,059		2,026
Deferred tax assets		395		295
Investments in partially-owned insurance companies		654		504
Other assets		4,042		3,556
Total assets		97,760		98,248
Liabilities
Unpaid losses and loss expenses		37,564		38,315
Unearned premiums		8,510		8,222
Future policy benefits		4,776		4,754
Insurance and reinsurance balances payable		4,225		4,095
Securities lending payable		1,012		1,331
Accounts payable, accrued expenses, and other liabilities		5,977		5,726
Short-term debt		2,103		2,552
Long-term debt		4,157		3,357
Trust preferred securities		309		309
Total liabilities		$ 68,633		$ 68,661
Commitments and contingencies
Shareholders’ equity
Common Shares (CHF 24.15 and CHF 24.77 par value; 342,832,412 shares issued; 324,062,368 and 328,659,686 shares outstanding)		$ 7,833		$ 8,055
Common Shares in treasury (18,770,044 and 14,172,726 shares)		(1,974)		(1,448)
Additional paid-in capital		4,665		5,145
Retained earnings		18,795		16,644
Accumulated other comprehensive income (loss) (AOCI)		(192)		1,191
Total shareholders’ equity		29,127		29,587
Total liabilities and shareholders’ equity		$ 97,760		$ 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 September 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 September 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.