Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income	$ 1,426	$ 3,216	$ 3,622
Net adjustments to reconcile net income to net cash provided by operating activities	743	(162)	609
Net cash provided by operating activities	2,169	3,054	4,231
Proceeds from maturities of fixed maturities	7,404	5,896	5,316
Proceeds from sales of investments, fixed maturities	1,161	3,713	2,805
Proceeds from sales of investments, equity securities	135	201	65
Proceeds from sales of investments, real estate	1	10
Proceeds from sales of investments, other investments	594	717	511
Purchases of investments, fixed maturities	(8,704)	(6,785)	(9,647)
Purchases of investments, equity securities	(131)	(61)	(24)
Purchases of investments, real estate	(66)	(21)	(15)
Purchases of investments, other investments	(889)	(514)	(349)
Net sales (purchases) of short-term securities	2,018	(699)	370
Securities transactions in course of settlement		(30)	395
Other investing activities	(371)	(318)	(326)
Net cash provided by (used in) investing activities	1,152	2,109	(899)
Payment of debt	(8)	(1,160)	(143)
Issuance of debt		1,234	494
Dividends paid to shareholders	(665)	(673)	(693)
Issuance of common stock - employee share options	314	408	180
Treasury shares acquired - share repurchase authorization	(2,919)	(4,998)	(3,259)
Treasury shares acquired - net employee share-based compensation	(46)	(40)	(29)
Excess tax benefits from share-based payment arrangements	18	8	8
Net cash used in financing activities	(3,306)	(5,221)	(3,442)
Effect of exchange rate changes on cash	(1)	3	15
Net increase (decrease) in cash	14	(55)	(95)
Cash at beginning of year	200	255	350
Cash at end of year	214	200	255
Income taxes paid (received)	218	784	876
Interest paid	382	397	385
TPC [Member]
Net income	1,182	2,464	2,633
Net adjustments to reconcile net income to net cash provided by operating activities	736	(77)	510
Net cash provided by operating activities	1,918	2,387	3,143
Proceeds from maturities of fixed maturities	4,902	3,920	2,903
Proceeds from sales of investments, fixed maturities	720	2,289	1,342
Proceeds from sales of investments, equity securities	82	29	20
Proceeds from sales of investments, real estate	1
Proceeds from sales of investments, other investments	343	338	253
Purchases of investments, fixed maturities	(5,714)	(4,201)	(5,368)
Purchases of investments, equity securities	(30)	(2)
Purchases of investments, real estate	(24)
Purchases of investments, other investments	(711)	(305)	(224)
Net sales (purchases) of short-term securities	717	632	(28)
Securities transactions in course of settlement	(46)	(4)	372
Other investing activities	(351)	(313)	(305)
Net cash provided by (used in) investing activities	(111)	2,383	(1,035)
Payment of debt		(4)	(2)
Dividends paid to parent company	(1,779)	(4,827)	(2,157)
Capital contributions, loans and other transactions between subsidiaries		15
Net cash used in financing activities	(1,779)	(4,816)	(2,159)
Net increase (decrease) in cash	28	(46)	(51)
Cash at beginning of year	86	132	183
Cash at end of year	114	86	132
Income taxes paid (received)	206	579	799
Interest paid	73	73	73
Other Subsidiaries [Member]
Net income	382	1,033	1,050
Net adjustments to reconcile net income to net cash provided by operating activities	98	(514)	276
Net cash provided by operating activities	480	519	1,326
Proceeds from maturities of fixed maturities	2,502	1,966	2,376
Proceeds from sales of investments, fixed maturities	440	1,424	1,457
Proceeds from sales of investments, equity securities	53	148	45
Proceeds from sales of investments, real estate		10
Proceeds from sales of investments, other investments	251	280	116
Purchases of investments, fixed maturities	(2,978)	(2,576)	(4,277)
Purchases of investments, equity securities	(71)	(33)	(24)
Purchases of investments, real estate	(42)	(21)	(15)
Purchases of investments, other investments	(178)	(209)	(125)
Net sales (purchases) of short-term securities	25	392	419
Securities transactions in course of settlement	46	(26)	23
Other investing activities	(20)	(5)	(21)
Net cash provided by (used in) investing activities	28	1,350	(26)
Payment of debt	(8)
Dividends paid to parent company	(521)	(1,849)	(1,340)
Capital contributions, loans and other transactions between subsidiaries	10	(35)	(20)
Net cash used in financing activities	(519)	(1,884)	(1,360)
Effect of exchange rate changes on cash	(1)	3	15
Net increase (decrease) in cash	(12)	(12)	(45)
Cash at beginning of year	110	122	167
Cash at end of year	98	110	122
Income taxes paid (received)	109	321	302
Travelers [Member]
Net income	1,426	3,216	3,622
Net adjustments to reconcile net income to net cash provided by operating activities	635	3,626	(345)
Net cash provided by operating activities	2,061	6,842	3,277
Proceeds from maturities of fixed maturities		10	37
Proceeds from sales of investments, fixed maturities	1		6
Proceeds from sales of investments, equity securities		24
Proceeds from sales of investments, other investments		99	142
Purchases of investments, fixed maturities	(12)	(8)	(2)
Purchases of investments, equity securities	(30)	(26)
Net sales (purchases) of short-term securities	1,276	(1,723)	(21)
Net cash provided by (used in) investing activities	1,235	(1,624)	162
Payment of debt		(1,156)	(141)
Issuance of debt		1,234	494
Dividends paid to shareholders	(665)	(673)	(693)
Issuance of common stock - employee share options	314	408	180
Treasury shares acquired - share repurchase authorization	(2,919)	(4,998)	(3,259)
Treasury shares acquired - net employee share-based compensation	(46)	(40)	(29)
Excess tax benefits from share-based payment arrangements	18	8	8
Capital contributions, loans and other transactions between subsidiaries		2	2
Net cash used in financing activities	(3,298)	(5,215)	(3,438)
Net increase (decrease) in cash	(2)	3	1
Cash at beginning of year	4	1
Cash at end of year	2	4	1
Income taxes paid (received)	(97)	(116)	(225)
Interest paid	309	324	312
Eliminations [Member]
Net income	(1,564)	(3,497)	(3,683)
Net adjustments to reconcile net income to net cash provided by operating activities	(726)	(3,197)	168
Net cash provided by operating activities	(2,290)	(6,694)	(3,515)
Dividends paid to parent company	2,300	6,676	3,497
Capital contributions, loans and other transactions between subsidiaries	(10)	18	18
Net cash used in financing activities	$ 2,290	$ 6,694	$ 3,515