Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Balance Sheet) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Investments	$ 62,904		$ 60,928
Cash	655	[1],[2]	579	[1],[3],[4]	615	[4],[5]	614	[5]
Insurance and reinsurance balances receivable	5,426		5,026
Reinsurance recoverable on losses and loss expenses	11,992		11,227
Reinsurance recoverable on policy benefits	217		218
Value of business acquired	466		536
Goodwill and other intangible assets	5,724		5,404
Other assets	10,864		10,592
Total assets	98,248		94,510
Unpaid losses and loss expenses	38,315		37,443		37,946		37,477
Unearned premiums	8,222		7,539
Future policy benefits	4,754		4,615
Bank Overdrafts			0	[3]
Short-term debt	2,552		1,901
Long-term debt	3,357		3,807
Trust preferred securities	309		309
Other liabilities	11,152		10,071
Total liabilities	68,661		65,685
Total shareholders' equity	29,587		28,825		27,531
Total liabilities and shareholders’ equity	98,248		94,510
ACE limited (Parent Gurantor)
Condensed Financial Statements, Captions [Line Items]
Investments	30		32
Cash	0	[1],[2]	0		103	[4],[5]	106	[5]
Investments in subsidiaries	29,497		28,351
Due from subsidiaries and affiliates, net	583		844
Other assets	4		5
Total assets	30,114		29,232
Bank Overdrafts	246	[2]	185	[3]
Other liabilities	281		222
Total liabilities	527		407
Total shareholders' equity	29,587		28,825
Total liabilities and shareholders’ equity	30,114		29,232
ACE INA Holdings Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Investments	225		10
Cash	1	[1],[2]	16	[1],[3],[4]	2	[4],[5]	5	[5]
Investments in subsidiaries	18,762		18,105
Other assets	295		258
Total assets	19,283		18,389
Due to subsidiaries and affiliates, net	422		714
Bank Overdrafts	309	[2]
Short-term debt	1,150		500
Long-term debt	3,345		3,795
Trust preferred securities	309		309
Other liabilities	1,404		1,318
Total liabilities	6,939		6,636
Total shareholders' equity	12,344		11,753
Total liabilities and shareholders’ equity	19,283		18,389
Other ACE Limited Subsidiaries and Eliminations
Condensed Financial Statements, Captions [Line Items]
Investments	62,649		60,886
Cash	1,209	[1],[2]	748	[1],[3],[4]	859	[4],[5]	651	[5]
Insurance and reinsurance balances receivable	6,178		5,835
Reinsurance recoverable on losses and loss expenses	20,992		20,057
Reinsurance recoverable on policy benefits	1,194		1,215
Value of business acquired	466		536
Goodwill and other intangible assets	5,724		5,404
Other assets	14,196		13,788
Total assets	112,608		108,469
Unpaid losses and loss expenses	46,770		45,714
Unearned premiums	9,958		9,242
Future policy benefits	5,731		5,612
Due to subsidiaries and affiliates, net	161		130
Short-term debt	1,402		1,401
Long-term debt	12		12
Other liabilities	12,659		11,655
Total liabilities	76,693		73,766
Total shareholders' equity	35,915		34,703
Total liabilities and shareholders’ equity	112,608		108,469
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Cash	(555)	[1],[2]	(185)	[1],[3],[4]	(349)	[4],[5]	(148)	[5]
Insurance and reinsurance balances receivable	(752)		(809)
Reinsurance recoverable on losses and loss expenses	(9,000)		(8,830)
Reinsurance recoverable on policy benefits	(977)		(997)
Investments in subsidiaries	(48,259)		(46,456)
Due from subsidiaries and affiliates, net	(583)		(844)
Other assets	(3,631)		(3,459)
Total assets	(63,757)		(61,580)
Unpaid losses and loss expenses	(8,455)		(8,271)
Unearned premiums	(1,736)		(1,703)
Future policy benefits	(977)		(997)
Due to subsidiaries and affiliates, net	(583)		(844)
Bank Overdrafts	(555)	[2]	(185)	[3]
Other liabilities	(3,192)		(3,124)
Total liabilities	(15,498)		(15,124)
Total shareholders' equity	(48,259)		(46,456)
Total liabilities and shareholders’ equity	$ (63,757)		$ (61,580)

[1] (1) ACE maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2014 and 2013, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[2] (1) ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] (1) ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2013, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[4] (1)ACE maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2013 and 2012, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[5] (1)ACE maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2012 and 2011, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.