Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Net income	$ 475	$ 1,317
Net adjustments to reconcile net income to net cash provided by operating activities	426	(266)
Net cash provided by operating activities	901	1,051
Proceeds from maturities of fixed maturities	3,234	2,478
Proceeds from sales of investments, fixed maturities	736	2,781
Proceeds from sales of investments, equity securities	47	27
Proceeds from sales of investments, real estate		10
Proceeds from sales of investments, other investments	285	189
Purchases of investments, fixed maturities	(3,547)	(3,940)
Purchases of investments, equity securities	(103)	(19)
Purchases of investments, real estate	(35)	(8)
Purchases of investments, other investments	(629)	(227)
Net sales (purchases) of short-term securities	597	1,050
Securities transactions in course of settlement	213	2
Other investing activities	(143)	(145)
Net cash provided by investing activities	655	2,198
Payment of debt	(8)	(250)
Dividends paid to shareholders	(329)	(343)
Issuance of common stock - employee share options	245	199
Treasury shares acquired - share repurchase authorization	(1,360)	(2,804)
Treasury shares acquired - net employee share-based compensation	(46)	(40)
Excess tax benefits from share-based payment arrangements, financing activities	11	5
Net cash used in financing activities	(1,487)	(3,233)
Effect of exchange rate changes on cash	4	(5)
Net increase (decrease) in cash	73	11
Cash at beginning of year	200	255
Cash at end of period	273	266
Income taxes paid (received)	291	309
Interest paid	191	200
TPC [Member]
Net income	456	1,137
Net adjustments to reconcile net income to net cash provided by operating activities	355	(164)
Net cash provided by operating activities	811	973
Proceeds from maturities of fixed maturities	1,969	1,540
Proceeds from sales of investments, fixed maturities	382	1,647
Proceeds from sales of investments, equity securities	15	19
Proceeds from sales of investments, other investments	183	136
Purchases of investments, fixed maturities	(2,342)	(2,432)
Purchases of investments, equity securities		(1)
Purchases of investments, real estate	(24)
Purchases of investments, other investments	(549)	(133)
Net sales (purchases) of short-term securities	(108)	1,147
Securities transactions in course of settlement	150	6
Other investing activities	(135)	(143)
Net cash provided by investing activities	(459)	1,786
Dividends paid to parent company	(353)	(2,782)
Net cash used in financing activities	(353)	(2,782)
Net increase (decrease) in cash	(1)	(23)
Cash at beginning of year	86	132
Cash at end of period	85	109
Income taxes paid (received)	199	235
Interest paid	36	36
Other Subsidiaries [Member]
Net income	43	323
Net adjustments to reconcile net income to net cash provided by operating activities	99	(494)
Net cash provided by operating activities	142	(171)
Proceeds from maturities of fixed maturities	1,265	928
Proceeds from sales of investments, fixed maturities	353	1,134
Proceeds from sales of investments, equity securities	32	8
Proceeds from sales of investments, real estate		10
Proceeds from sales of investments, other investments	102	53
Purchases of investments, fixed maturities	(1,204)	(1,508)
Purchases of investments, equity securities	(74)	(18)
Purchases of investments, real estate	(11)	(8)
Purchases of investments, other investments	(80)	(94)
Net sales (purchases) of short-term securities	(500)	432
Securities transactions in course of settlement	63	(4)
Other investing activities	(8)	(2)
Net cash provided by investing activities	(62)	931
Payment of debt	(8)
Dividends paid to parent company		(721)
Net cash used in financing activities	(8)	(721)
Effect of exchange rate changes on cash	4	(5)
Net increase (decrease) in cash	76	34
Cash at beginning of year	110	122
Cash at end of period	186	156
Income taxes paid (received)	114	119
Travelers [Member]
Net income	475	1,317
Net adjustments to reconcile net income to net cash provided by operating activities	(174)	2,434
Net cash provided by operating activities	301	3,751
Proceeds from maturities of fixed maturities		10
Proceeds from sales of investments, fixed maturities	1
Purchases of investments, fixed maturities	(1)
Purchases of investments, equity securities	(29)
Net sales (purchases) of short-term securities	1,205	(529)
Net cash provided by investing activities	1,176	(519)
Payment of debt		(250)
Dividends paid to shareholders	(329)	(343)
Issuance of common stock - employee share options	245	199
Treasury shares acquired - share repurchase authorization	(1,360)	(2,804)
Treasury shares acquired - net employee share-based compensation	(46)	(40)
Excess tax benefits from share-based payment arrangements, financing activities	11	5
Capital contributions and loans between subsidiaries		1
Net cash used in financing activities	(1,479)	(3,232)
Net increase (decrease) in cash	(2)
Cash at beginning of year	4	1
Cash at end of period	2	1
Income taxes paid (received)	(22)	(45)
Interest paid	155	164
Eliminations [Member]
Net income	(499)	(1,460)
Net adjustments to reconcile net income to net cash provided by operating activities	146	(2,042)
Net cash provided by operating activities	(353)	(3,502)
Dividends paid to parent company	353	3,503
Capital contributions and loans between subsidiaries		(1)
Net cash used in financing activities	$ 353	$ 3,502