Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Consolidating financial statements
Net income	$ 896	$ 806
Net adjustments to reconcile net income to net cash provided by operating activities	(366)	8
Net cash provided by operating activities	530	814
Proceeds from maturities of fixed maturities	2,123	1,615
Proceeds from sales of investments, fixed maturities	234	223
Proceeds from sales of investments, equity securities	36	15
Proceeds from sales of investments, other investments	174	203
Purchases of investments, fixed maturities	(2,339)	(2,604)
Purchases of investments, equity securities	(13)	(10)
Purchases of investments, real estate investments	(6)	(5)
Purchases of investments, other investments	(95)	(114)
Net (purchases) sales of short-term securities	109	226
Securities transactions in course of settlement	180	248
Other investing activities	(100)	(92)
Net cash provided by (used in) investing activities	303	(295)
Payment of debt	(500)
Dividends paid to shareholders	(175)	(161)
Issuance of common stock - employee share options	98	77
Treasury stock acquired - share repurchase authorization	(300)	(354)
Treasury stock acquired - net employee share-based compensation	(58)	(52)
Excess tax benefits from share-based payment arrangements	21	12
Net cash used in financing activities	(914)	(478)
Effect of exchange rate changes on cash	(6)	3
Net increase (decrease) in cash	(87)	44
Cash at beginning of year	330	214
Cash at end of period	243	258
Income taxes paid (received)	27	20
Interest paid	35	35
TPC [Member]
Consolidating financial statements
Net income	650	618
Net adjustments to reconcile net income to net cash provided by operating activities	(251)	20
Net cash provided by operating activities	399	638
Proceeds from maturities of fixed maturities	1,345	1,034
Proceeds from sales of investments, fixed maturities	170	189
Proceeds from sales of investments, equity securities	10	12
Proceeds from sales of investments, other investments	101	162
Purchases of investments, fixed maturities	(1,453)	(1,876)
Purchases of investments, equity securities	(5)	(1)
Purchases of investments, other investments	(62)	(66)
Net (purchases) sales of short-term securities	(326)	(63)
Securities transactions in course of settlement	95	209
Other investing activities	(99)	(88)
Net cash provided by (used in) investing activities	(224)	(488)
Payment of debt	(500)
Capital contributions	500
Dividends paid to parent company	(217)	(154)
Net cash used in financing activities	(217)	(154)
Net increase (decrease) in cash	(42)	(4)
Cash at beginning of year	177	114
Cash at end of period	135	110
Income taxes paid (received)	97	48
Interest paid	28	28
Other Subsidiaries [Member]
Consolidating financial statements
Net income	293	249
Net adjustments to reconcile net income to net cash provided by operating activities	(276)	(164)
Net cash provided by operating activities	17	85
Proceeds from maturities of fixed maturities	778	581
Proceeds from sales of investments, fixed maturities	60	34
Proceeds from sales of investments, equity securities	26	3
Proceeds from sales of investments, other investments	73	41
Purchases of investments, fixed maturities	(886)	(728)
Purchases of investments, equity securities	(8)	(9)
Purchases of investments, real estate investments	(6)	(5)
Purchases of investments, other investments	(33)	(48)
Net (purchases) sales of short-term securities	(43)	116
Securities transactions in course of settlement	85	39
Other investing activities	(1)	(4)
Net cash provided by (used in) investing activities	45	20
Dividends paid to parent company	(100)	(58)
Net cash used in financing activities	(100)	(58)
Effect of exchange rate changes on cash	(6)	3
Net increase (decrease) in cash	(44)	50
Cash at beginning of year	151	98
Cash at end of period	107	148
Income taxes paid (received)	24	18
Travelers [Member]
Consolidating financial statements
Net income	896	806
Net adjustments to reconcile net income to net cash provided by operating activities	(965)	(503)
Net cash provided by operating activities	(69)	303
Proceeds from sales of investments, fixed maturities	4
Net (purchases) sales of short-term securities	478	173
Net cash provided by (used in) investing activities	482	173
Dividends paid to shareholders	(175)	(161)
Issuance of common stock - employee share options	98	77
Treasury stock acquired - share repurchase authorization	(300)	(354)
Treasury stock acquired - net employee share-based compensation	(58)	(52)
Excess tax benefits from share-based payment arrangements	21	12
Net cash used in financing activities	(414)	(478)
Net increase (decrease) in cash	(1)	(2)
Cash at beginning of year	2	2
Cash at end of period	1
Income taxes paid (received)	(94)	(46)
Interest paid	7	7
Eliminations [Member]
Consolidating financial statements
Net income	(943)	(867)
Net adjustments to reconcile net income to net cash provided by operating activities	1,126	655
Net cash provided by operating activities	183	(212)
Capital contributions	(500)
Dividends paid to parent company	317	212
Net cash used in financing activities	$ (183)	$ 212