Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Consolidating Statement of Comprehensive Income
Net income	$ 812	$ 683	$ 1,645	$ 1,735
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(1,065)	518	(896)	1,055
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(5)	1	(10)	3
Net changes in benefit plan assets and obligations	23	15	47	30
Net changes in unrealized foreign currency translation	94	97	(180)	54
Other comprehensive income (loss) before income taxes	(953)	631	(1,039)	1,142
Income tax expense (benefit)	(353)	196	(328)	390
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(600)	435	(711)	752
Other comprehensive income (loss), net of taxes	(600)	435	(711)	752
Comprehensive income	212	1,118	934	2,487
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Comprehensive Income
Net income	628	526	1,260	1,309
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(719)	359	(585)	750
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(5)	2	(9)	9
Net changes in benefit plan assets and obligations	1		1
Net changes in unrealized foreign currency translation	34	51	(145)	26
Other comprehensive income (loss) before income taxes	(689)	412	(738)	785
Income tax expense (benefit)	(246)	129	(232)	272
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(443)	283	(506)	513
Other comprehensive income (loss), net of taxes	(443)	283	(506)	513
Comprehensive income	185	809	754	1,822
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income	245	211	500	532
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(345)	155	(312)	301
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income		(1)	(1)	(6)
Net changes in benefit plan assets and obligations			1
Net changes in unrealized foreign currency translation	60	46	(35)	28
Other comprehensive income (loss) before income taxes	(285)	200	(347)	323
Income tax expense (benefit)	(115)	61	(112)	106
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(170)	139	(235)	217
Other comprehensive income (loss), net of taxes	(170)	139	(235)	217
Comprehensive income	75	350	265	749
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Comprehensive Income
Net income	812	683	1,645	1,735
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(1)	4	1	4
Net changes in benefit plan assets and obligations	22	15	45	30
Other comprehensive income (loss) before income taxes	21	19	46	34
Income tax expense (benefit)	8	6	16	12
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	13	13	30	22
Other comprehensive income (loss) of subsidiaries	(613)	422	(741)	730
Other comprehensive income (loss), net of taxes	(600)	435	(711)	752
Comprehensive income	212	1,118	934	2,487
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income	(873)	(737)	(1,760)	(1,841)
Other comprehensive income (loss) of subsidiaries	613	(422)	741	(730)
Other comprehensive income (loss), net of taxes	613	(422)	741	(730)
Comprehensive income	$ (260)	$ (1,159)	$ (1,019)	$ (2,571)