Schedule II (details) - Condensed Statement of Comprehensive Income (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
Condensed Statement of Comprehensive Income
Consolidated 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
Travelers [Member] | Reportable Legal Entities [Member]
Condensed Statement of Comprehensive Income
Consolidated 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