Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income	$ 806	$ 839
Net adjustments to reconcile net income to net cash provided by operating activities	8	(206)
Net cash provided by operating activities	814	633
Proceeds from maturities of fixed maturities	1,615	1,849
Proceeds from sales of investments, fixed maturities	223	490
Proceeds from sales of investments, equity securities	15	8
Proceeds from sales of investments, other investments	203	161
Purchases of investments, fixed maturities	(2,604)	(1,824)
Purchases of investments, equity securities	(10)	(51)
Purchases of investments, real estate investments	(5)	(30)
Purchases of investments, other investments	(114)	(107)
Net (purchases) sales of short-term securities	226	(31)
Securities transactions in course of settlement	248	134
Other investing activities	(92)	(69)
Net cash provided by (used in) investing activities	(295)	530
Dividends paid to shareholders	(161)	(155)
Issuance of common stock - employee share options	77	168
Treasury shares acquired - share repurchase authorization	(354)	(1,104)
Treasury shares acquired - net employee share-based compensation	(52)	(44)
Excess tax benefits from share-based payment arrangements	12	7
Net cash used in financing activities	(478)	(1,128)
Effect of exchange rate changes on cash	3	4
Net increase in cash	44	39
Cash at beginning of year	214	200
Cash at end of period	258	239
Income taxes paid (received)	20	112
Interest paid	35	35
TPC [Member]
Net income	618	600
Net adjustments to reconcile net income to net cash provided by operating activities	20	(3)
Net cash provided by operating activities	638	597
Proceeds from maturities of fixed maturities	1,034	1,132
Proceeds from sales of investments, fixed maturities	189	230
Proceeds from sales of investments, equity securities	12	1
Proceeds from sales of investments, other investments	162	102
Purchases of investments, fixed maturities	(1,876)	(1,210)
Purchases of investments, equity securities	(1)
Purchases of investments, real estate investments		(24)
Purchases of investments, other investments	(66)	(65)
Net (purchases) sales of short-term securities	(63)	(384)
Securities transactions in course of settlement	209	79
Other investing activities	(88)	(68)
Net cash provided by (used in) investing activities	(488)	(207)
Dividends paid to parent company	(154)	(353)
Net cash used in financing activities	(154)	(353)
Net increase in cash	(4)	37
Cash at beginning of year	114	86
Cash at end of period	110	123
Income taxes paid (received)	48	75
Interest paid	28	28
Other Subsidiaries [Member]
Net income	249	189
Net adjustments to reconcile net income to net cash provided by operating activities	(164)	(186)
Net cash provided by operating activities	85	3
Proceeds from maturities of fixed maturities	581	717
Proceeds from sales of investments, fixed maturities	34	259
Proceeds from sales of investments, equity securities	3	7
Proceeds from sales of investments, other investments	41	59
Purchases of investments, fixed maturities	(728)	(612)
Purchases of investments, equity securities	(9)	(23)
Purchases of investments, real estate investments	(5)	(6)
Purchases of investments, other investments	(48)	(42)
Net (purchases) sales of short-term securities	116	(418)
Securities transactions in course of settlement	39	55
Other investing activities	(4)	(1)
Net cash provided by (used in) investing activities	20	(5)
Dividends paid to parent company	(58)
Net cash used in financing activities	(58)
Effect of exchange rate changes on cash	3	4
Net increase in cash	50	2
Cash at beginning of year	98	110
Cash at end of period	148	112
Income taxes paid (received)	18	36
Travelers [Member]
Net income	806	839
Net adjustments to reconcile net income to net cash provided by operating activities	(503)	(453)
Net cash provided by operating activities	303	386
Proceeds from sales of investments, fixed maturities		1
Purchases of investments, fixed maturities		(2)
Purchases of investments, equity securities		(28)
Net (purchases) sales of short-term securities	173	771
Net cash provided by (used in) investing activities	173	742
Dividends paid to shareholders	(161)	(155)
Issuance of common stock - employee share options	77	168
Treasury shares acquired - share repurchase authorization	(354)	(1,104)
Treasury shares acquired - net employee share-based compensation	(52)	(44)
Excess tax benefits from share-based payment arrangements	12	7
Net cash used in financing activities	(478)	(1,128)
Net increase in cash	(2)
Cash at beginning of year	2	4
Cash at end of period		4
Income taxes paid (received)	(46)	1
Interest paid	7	7
Eliminations [Member]
Net income	(867)	(789)
Net adjustments to reconcile net income to net cash provided by operating activities	655	436
Net cash provided by operating activities	(212)	(353)
Dividends paid to parent company	212	353
Net cash used in financing activities	$ 212	$ 353