Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidating Statement of Comprehensive Income
Net income	$ 1,038	$ 919	$ 683	$ 1,052	$ 988	$ 864	$ 925	$ 896	$ 3,692	$ 3,673	$ 2,473
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									976	(2,734)	281
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									2	3	81
Net changes in benefit plan assets and obligations									(494)	647	(69)
Net changes in unrealized foreign currency translation									(289)	(112)	43
Other comprehensive income (loss) before income taxes									195	(2,196)	336
Income tax expense (benefit)									125	(770)	105
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									70	(1,426)	231
Other comprehensive income (loss), net of taxes									70	(1,426)	231
Comprehensive income									3,762	2,247	2,704
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Comprehensive Income
Net income									2,780	2,771	1,857
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									681	(1,982)	248
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									9	4	57
Net changes in benefit plan assets and obligations									(15)	12	(6)
Net changes in unrealized foreign currency translation									(173)	(92)	(19)
Other comprehensive income (loss) before income taxes									502	(2,058)	280
Income tax expense (benefit)									207	(719)	101
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									295	(1,339)	179
Other comprehensive income (loss), net of taxes									295	(1,339)	179
Comprehensive income									3,075	1,432	2,036
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income									1,124	1,044	798
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									289	(771)	23
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(7)	(1)	24
Net changes in benefit plan assets and obligations									(8)	19	(5)
Net changes in unrealized foreign currency translation									(116)	(20)	62
Other comprehensive income (loss) before income taxes									158	(773)	104
Income tax expense (benefit)									81	(273)	21
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									77	(500)	83
Other comprehensive income (loss), net of taxes									77	(500)	83
Comprehensive income									1,201	544	881
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Comprehensive Income
Net income									3,692	3,673	2,473
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									6	19	10
Net changes in benefit plan assets and obligations									(471)	616	(58)
Other comprehensive income (loss) before income taxes									(465)	635	(48)
Income tax expense (benefit)									(163)	222	(17)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(302)	413	(31)
Other comprehensive income (loss) of subsidiaries									372	(1,839)	262
Other comprehensive income (loss), net of taxes									70	(1,426)	231
Comprehensive income									3,762	2,247	2,704
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income									(3,904)	(3,815)	(2,655)
Other comprehensive income (loss) of subsidiaries									(372)	1,839	(262)
Other comprehensive income (loss), net of taxes									(372)	1,839	(262)
Comprehensive income									$ (4,276)	$ (1,976)	$ (2,917)