Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) - 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
Consolidating 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)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(14)	2	3
Net changes in benefit plan assets and obligations									66	(494)	647
Net changes in unrealized foreign currency translation									(461)	(289)	(112)
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
TPC [Member]
Consolidating Statement of Comprehensive Income
Net income									2,666	2,780	2,771
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(610)	681	(1,982)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(12)	9	4
Net changes in benefit plan assets and obligations									2	(15)	12
Net changes in unrealized foreign currency translation									(306)	(173)	(92)
Other comprehensive income (loss) before income taxes									(926)	502	(2,058)
Income tax expense (benefit)									(257)	207	(719)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(669)	295	(1,339)
Other comprehensive income (loss), net of taxes									(669)	295	(1,339)
Comprehensive income									1,997	3,075	1,432
Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income									998	1,124	1,044
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(407)	289	(771)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(2)	(7)	(1)
Net changes in benefit plan assets and obligations										(8)	19
Net changes in unrealized foreign currency translation									(155)	(116)	(20)
Other comprehensive income (loss) before income taxes									(564)	158	(773)
Income tax expense (benefit)									(156)	81	(273)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(408)	77	(500)
Other comprehensive income (loss), net of taxes									(408)	77	(500)
Comprehensive income									590	1,201	544
Travelers [Member]
Consolidating 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
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income									(3,664)	(3,904)	(3,815)
Other comprehensive income (loss) of subsidiaries									1,077	(372)	1,839
Other comprehensive income (loss), net of taxes									1,077	(372)	1,839
Comprehensive income									$ (2,587)	$ (4,276)	$ (1,976)