Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Cash flows from operating activities
Net income	$ 953		$ 973
Adjustments to reconcile net income to net cash flows from operating activities
Net realized (gains) losses	(206)		(260)
Amortization of premiums/discounts on fixed maturities	66		45
Deferred income taxes	35		(1)
Unpaid losses and loss expenses	(505)		(492)
Unearned premiums	267		265
Future policy benefits	44		27
Insurance and reinsurance balances payable	(41)		(126)
Accounts payable, accrued expenses, and other liabilities	144		(65)
Income taxes payable	29		41
Insurance and reinsurance balances receivable	(45)		(58)
Reinsurance recoverable on losses and loss expenses	435		422
Reinsurance recoverable on policy benefits	10		11
Deferred policy acquisition costs	(121)		(72)
Prepaid reinsurance premiums	(58)		(83)
Other	(94)		(55)
Net cash flows from operating activities	913		572
Cash flows from investing activities
Purchases of fixed maturities available for sale	(6,133)		(5,429)
Purchases of to be announced mortgage-backed securities	(19)		(54)
Purchases of fixed maturities held to maturity	(142)		(32)
Purchases of equity securities	(107)		(19)
Sales of fixed maturities available for sale	2,745		3,736
Sales of to be announced mortgage-backed securities	19		59
Sales of equity securities	31		26
Maturities and redemptions of fixed maturities available for sale	2,016		1,076
Maturities and redemptions of fixed maturities held to maturity	491		345
Net derivative instruments settlements	(279)		(195)
Acquisition of subsidiaries	(33)		(25)
Other	(55)		(103)
Net cash flows used for investing activities	(1,466)		(615)
Cash flows from financing activities
Dividends paid on Common Shares	(2)		(159)
Common Shares repurchased	(154)		(11)
Proceeds from issuance of long-term debt	947		0
Proceeds from issuance of short-term debt	659		681
Repayment of short-term debt	(658)		(400)
Proceeds from share-based compensation plans, including windfall tax benefits	21		28
Net cash flows from financing activities	813		139
Effect of foreign currency rate changes on cash and cash equivalents	(20)		5
Net increase (decrease) in cash	240		101
Cash - beginning of period	615	[1]	614
Cash - end of period	855		715
Supplemental cash flow information
Taxes paid	43		72
Interest paid	$ 31		$ 37

[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 December 31, 2012, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.