Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Consolidating Statement of Comprehensive Income
Net income	$ 928	$ 919	$ 2,573	$ 2,654
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	67	(154)	(829)	901
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(3)	1	(13)	4
Net changes in benefit plan assets and obligations	24	15	71	45
Net changes in unrealized foreign currency translation	(227)	(203)	(407)	(149)
Other comprehensive income (loss) before income taxes	(139)	(341)	(1,178)	801
Income tax expense (benefit)	(2)	(79)	(330)	311
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(137)	(262)	(848)	490
Other comprehensive income (loss), net of taxes	(137)	(262)	(848)	490
Comprehensive income	791	657	1,725	3,144
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Comprehensive Income
Net income	699	687	1,959	1,996
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	93	(118)	(492)	632
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(2)	2	(11)	11
Net changes in benefit plan assets and obligations	1		2
Net changes in unrealized foreign currency translation	(148)	(120)	(293)	(94)
Other comprehensive income (loss) before income taxes	(56)	(236)	(794)	549
Income tax expense (benefit)	8	(62)	(224)	210
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(64)	(174)	(570)	339
Other comprehensive income (loss), net of taxes	(64)	(174)	(570)	339
Comprehensive income	635	513	1,389	2,335
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income	287	285	787	817
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(17)	(35)	(329)	266
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(1)	(1)	(2)	(7)
Net changes in benefit plan assets and obligations	1	1	2	1
Net changes in unrealized foreign currency translation	(79)	(83)	(114)	(55)
Other comprehensive income (loss) before income taxes	(96)	(118)	(443)	205
Income tax expense (benefit)	(14)	(22)	(126)	84
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(82)	(96)	(317)	121
Other comprehensive income (loss), net of taxes	(82)	(96)	(317)	121
Comprehensive income	205	189	470	938
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Comprehensive Income
Net income	928	919	2,573	2,654
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(9)	(1)	(8)	3
Net changes in benefit plan assets and obligations	22	14	67	44
Other comprehensive income (loss) before income taxes	13	13	59	47
Income tax expense (benefit)	4	5	20	17
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	9	8	39	30
Other comprehensive income (loss) of subsidiaries	(146)	(270)	(887)	460
Other comprehensive income (loss), net of taxes	(137)	(262)	(848)	490
Comprehensive income	791	657	1,725	3,144
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income	(986)	(972)	(2,746)	(2,813)
Other comprehensive income (loss) of subsidiaries	146	270	887	(460)
Other comprehensive income (loss), net of taxes	146	270	887	(460)
Comprehensive income	$ (840)	$ (702)	$ (1,859)	$ (3,273)