Schedule II (details) - Condensed Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Statement of Comprehensive Income
Net income	$ 866	$ 928	$ 812	$ 833	$ 1,038	$ 919	$ 683	$ 1,052	$ 3,439	$ 3,692	$ 3,673
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(1,020)	976	(2,734)
Net changes in benefit plan assets and obligations									66	(494)	647
Other comprehensive income (loss) before income taxes									(1,429)	195	(2,196)
Income tax expense (benefit)									(392)	125	(770)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(1,037)	70	(1,426)
Other comprehensive income (loss), net of taxes									(1,037)	70	(1,426)
Comprehensive income									2,402	3,762	2,247
Travelers [Member]
Condensed Statement of Comprehensive Income
Net income									3,439	3,692	3,673
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(3)	6	19
Net changes in benefit plan assets and obligations									64	(471)	616
Other comprehensive income (loss) before income taxes									61	(465)	635
Income tax expense (benefit)									21	(163)	222
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									40	(302)	413
Other comprehensive income (loss) of subsidiaries									(1,077)	372	(1,839)
Other comprehensive income (loss), net of taxes									(1,037)	70	(1,426)
Comprehensive income									$ 2,402	$ 3,762	$ 2,247