Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Net income	$ 808	$ 2,322
Net adjustments to reconcile net income to net cash provided by operating activities	1,010	70
Net cash provided by operating activities	1,818	2,392
Proceeds from maturities of fixed maturities	5,241	3,881
Proceeds from sales of investments, fixed maturities	842	3,281
Proceeds from sales of investments, equity securities	51	157
Proceeds from sales of investments, real estate	1	10
Proceeds from sales of investments, other investments	482	426
Purchases of investments, fixed maturities	(6,224)	(5,167)
Purchases of investments, equity securities	(118)	(29)
Purchases of investments, real estate	(41)	(15)
Purchases of investments, other investments	(758)	(373)
Net sales (purchases) of short-term securities	813	(66)
Securities transactions in course of settlement	196	(240)
Other investing activities	(248)	(220)
Net cash provided by (used in) investing activities	237	1,645
Payment of debt	(8)	(275)
Dividends paid to shareholders	(500)	(512)
Issuance of common stock - employee share options	270	267
Treasury shares acquired - share repurchase authorization	(1,755)	(3,441)
Treasury shares acquired - net employee share-based compensation	(46)	(40)
Excess tax benefits from share-based payment arrangements	17	6
Net cash used in financing activities	(2,022)	(3,995)
Effect of exchange rate changes on cash	(2)	1
Net increase in cash	31	43
Cash at beginning of year	200	255
Cash at end of period	231	298
Income taxes paid (received)	277	511
Interest paid	226	263
TPC [Member]
Net income	710	1,766
Net adjustments to reconcile net income to net cash provided by operating activities	764	191
Net cash provided by operating activities	1,474	1,957
Proceeds from maturities of fixed maturities	3,490	2,507
Proceeds from sales of investments, fixed maturities	452	2,045
Proceeds from sales of investments, equity securities	15	30
Proceeds from sales of investments, real estate	1
Proceeds from sales of investments, other investments	301	213
Purchases of investments, fixed maturities	(4,131)	(3,212)
Purchases of investments, equity securities	(6)	(3)
Purchases of investments, real estate	(24)
Purchases of investments, other investments	(622)	(221)
Net sales (purchases) of short-term securities	54	826
Securities transactions in course of settlement	128	23
Other investing activities	(234)	(216)
Net cash provided by (used in) investing activities	(576)	1,992
Payment of debt		(4)
Dividends paid to parent company	(878)	(3,952)
Capital contributions, loans and other transactions between subsidiaries		11
Net cash used in financing activities	(878)	(3,945)
Net increase in cash	20	4
Cash at beginning of year	86	132
Cash at end of period	106	136
Income taxes paid (received)	221	399
Interest paid	65	65
Other Subsidiaries [Member]
Net income	173	737
Net adjustments to reconcile net income to net cash provided by operating activities	214	(548)
Net cash provided by operating activities	387	189
Proceeds from maturities of fixed maturities	1,751	1,364
Proceeds from sales of investments, fixed maturities	389	1,236
Proceeds from sales of investments, equity securities	36	127
Proceeds from sales of investments, real estate		10
Proceeds from sales of investments, other investments	181	213
Purchases of investments, fixed maturities	(2,092)	(1,947)
Purchases of investments, equity securities	(73)	(26)
Purchases of investments, real estate	(17)	(15)
Purchases of investments, other investments	(136)	(152)
Net sales (purchases) of short-term securities	(470)	38
Securities transactions in course of settlement	68	(263)
Other investing activities	(14)	(4)
Net cash provided by (used in) investing activities	(377)	581
Payment of debt	(8)
Dividends paid to parent company		(721)
Capital contributions, loans and other transactions between subsidiaries	10	(12)
Net cash used in financing activities	2	(733)
Effect of exchange rate changes on cash	(2)	1
Net increase in cash	10	38
Cash at beginning of year	110	122
Cash at end of period	120	160
Income taxes paid (received)	83	186
Travelers [Member]
Net income	808	2,322
Net adjustments to reconcile net income to net cash provided by operating activities	17	2,596
Net cash provided by operating activities	825	4,918
Proceeds from maturities of fixed maturities		10
Proceeds from sales of investments, fixed maturities	1
Purchases of investments, fixed maturities	(1)	(8)
Purchases of investments, equity securities	(39)
Net sales (purchases) of short-term securities	1,229	(930)
Net cash provided by (used in) investing activities	1,190	(928)
Payment of debt		(271)
Dividends paid to shareholders	(500)	(512)
Issuance of common stock - employee share options	270	267
Treasury shares acquired - share repurchase authorization	(1,755)	(3,441)
Treasury shares acquired - net employee share-based compensation	(46)	(40)
Excess tax benefits from share-based payment arrangements	17	6
Capital contributions, loans and other transactions between subsidiaries		2
Net cash used in financing activities	(2,014)	(3,989)
Net increase in cash	1	1
Cash at beginning of year	4	1
Cash at end of period	5	2
Income taxes paid (received)	(27)	(74)
Interest paid	161	198
Eliminations [Member]
Net income	(883)	(2,503)
Net adjustments to reconcile net income to net cash provided by operating activities	15	(2,169)
Net cash provided by operating activities	(868)	(4,672)
Dividends paid to parent company	878	4,673
Capital contributions, loans and other transactions between subsidiaries	(10)	(1)
Net cash used in financing activities	$ 868	$ 4,672