Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Consolidating Statement of Cash Flows
Net income	$ 2,685	$ 2,169
Net adjustments to reconcile net income to net cash provided by operating activities	204	597
Net cash provided by operating activities	2,889	2,766
Proceeds from maturities of fixed maturities	5,917	5,855
Proceeds from sales of investments, fixed maturities	1,160	724
Proceeds from sales of investments, equity securities	57	31
Proceeds from sales of investments, real estate investments		3
Proceeds from sales of investments, other investments	545	516
Purchases of investments, fixed maturities	(6,492)	(7,677)
Purchases of investments, equity securities	(50)	(39)
Purchases of investments, real estate investments	(65)	(62)
Purchases of investments, other investments	(312)	(292)
Net sales (purchases) of short-term securities	(1,893)	(41)
Securities transactions in course of settlement	280	53
Other investing activities	(254)	(229)
Net cash used in investing activities	(1,107)	(1,158)
Payment of debt	(500)	(258)
Issuance of debt	494
Dividends paid to shareholders	(549)	(519)
Issuance of common stock - employee share options	158	247
Treasury stock acquired - share repurchase authorization	(1,400)	(1,056)
Treasury stock acquired - net employee share-based compensation	(60)	(52)
Excess tax benefits from share-based payment arrangements	43	32
Net cash used in financing activities	(1,814)	(1,606)
Effect of exchange rate changes on cash	(3)	4
Net increase (decrease) in cash	(35)	6
Cash at beginning of year	330	214
Cash at end of period	295	220
Income taxes paid (received)	724	310
Interest paid	206	226
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Cash Flows
Net income	2,056	1,610
Net adjustments to reconcile net income to net cash provided by operating activities	(348)	552
Net cash provided by operating activities	1,708	2,162
Proceeds from maturities of fixed maturities	4,096	4,123
Proceeds from sales of investments, fixed maturities	590	494
Proceeds from sales of investments, equity securities	21	18
Proceeds from sales of investments, other investments	337	389
Purchases of investments, fixed maturities	(4,339)	(5,645)
Purchases of investments, equity securities	(20)	(1)
Purchases of investments, other investments	(222)	(187)
Net sales (purchases) of short-term securities	(1,563)	(306)
Securities transactions in course of settlement	182	46
Other investing activities	(250)	(235)
Net cash used in investing activities	(1,168)	(1,304)
Payment of debt	(500)
Capital contributions	500
Dividends paid to parent company	(587)	(854)
Net cash used in financing activities	(587)	(854)
Net increase (decrease) in cash	(47)	4
Cash at beginning of year	177	114
Cash at end of period	130	118
Income taxes paid (received)	691	343
Interest paid	52	65
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Cash Flows
Net income	775	704
Net adjustments to reconcile net income to net cash provided by operating activities	224	(136)
Net cash provided by operating activities	999	568
Proceeds from maturities of fixed maturities	1,820	1,731
Proceeds from sales of investments, fixed maturities	565	228
Proceeds from sales of investments, equity securities	36	13
Proceeds from sales of investments, real estate investments		3
Proceeds from sales of investments, other investments	208	127
Purchases of investments, fixed maturities	(2,146)	(2,023)
Purchases of investments, equity securities	(29)	(37)
Purchases of investments, real estate investments	(65)	(62)
Purchases of investments, other investments	(90)	(105)
Net sales (purchases) of short-term securities	(492)	(99)
Securities transactions in course of settlement	98	7
Other investing activities	(4)	6
Net cash used in investing activities	(99)	(211)
Dividends paid to parent company	(885)	(358)
Net cash used in financing activities	(885)	(358)
Effect of exchange rate changes on cash	(3)	4
Net increase (decrease) in cash	12	3
Cash at beginning of year	151	98
Cash at end of period	163	101
Income taxes paid (received)	236	110
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Cash Flows
Net income	2,685	2,169
Net adjustments to reconcile net income to net cash provided by operating activities	(1,531)	(921)
Net cash provided by operating activities	1,154	1,248
Proceeds from maturities of fixed maturities	1	1
Proceeds from sales of investments, fixed maturities	5	2
Purchases of investments, fixed maturities	(7)	(9)
Purchases of investments, equity securities	(1)	(1)
Net sales (purchases) of short-term securities	162	364
Net cash used in investing activities	160	357
Payment of debt		(258)
Issuance of debt	494
Dividends paid to shareholders	(549)	(519)
Issuance of common stock - employee share options	158	247
Treasury stock acquired - share repurchase authorization	(1,400)	(1,056)
Treasury stock acquired - net employee share-based compensation	(60)	(52)
Excess tax benefits from share-based payment arrangements	43	32
Net cash used in financing activities	(1,314)	(1,606)
Net increase (decrease) in cash		(1)
Cash at beginning of year	2	2
Cash at end of period	2	1
Income taxes paid (received)	(203)	(143)
Interest paid	154	161
Eliminations [Member]
Consolidating Statement of Cash Flows
Net income	(2,831)	(2,314)
Net adjustments to reconcile net income to net cash provided by operating activities	1,859	1,102
Net cash provided by operating activities	(972)	(1,212)
Capital contributions	(500)
Dividends paid to parent company	1,472	1,212
Net cash used in financing activities	$ 972	$ 1,212