Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Consolidating Statement of Comprehensive Income
Net income	$ 833	$ 1,052
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	169	537
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(5)	2
Net changes in benefit plan assets and obligations	24	15
Net changes in unrealized foreign currency translation	(274)	(43)
Other comprehensive income (loss) before income taxes	(86)	511
Income tax expense	25	194
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(111)	317
Other comprehensive income (loss), net of taxes	(111)	317
Comprehensive income	722	1,369
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Comprehensive Income
Net income	632	783
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	134	391
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(4)	7
Net changes in unrealized foreign currency translation	(179)	(25)
Other comprehensive income (loss) before income taxes	(49)	373
Income tax expense	14	143
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(63)	230
Other comprehensive income (loss), net of taxes	(63)	230
Comprehensive income	569	1,013
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income	255	321
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	33	146
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(1)	(5)
Net changes in benefit plan assets and obligations	1
Net changes in unrealized foreign currency translation	(95)	(18)
Other comprehensive income (loss) before income taxes	(62)	123
Income tax expense	3	45
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	(65)	78
Other comprehensive income (loss), net of taxes	(65)	78
Comprehensive income	190	399
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Comprehensive Income
Net income	833	1,052
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	2
Net changes in benefit plan assets and obligations	23	15
Other comprehensive income (loss) before income taxes	25	15
Income tax expense	8	6
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries	17	9
Other comprehensive income (loss) of subsidiaries	(128)	308
Other comprehensive income (loss), net of taxes	(111)	317
Comprehensive income	722	1,369
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income	(887)	(1,104)
Other comprehensive income (loss) of subsidiaries	128	(308)
Other comprehensive income (loss), net of taxes	128	(308)
Comprehensive income	$ (759)	$ (1,412)