Consolidating Financial Statements (details) - Consolidated Statement of Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidating financial statements
Net income	$ 304	$ 864	$ 499	$ 806	$ 618	$ 333	$ (364)	$ 839	$ 2,473	$ 1,426	$ 3,216
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									281	1,570	(118)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									81	4	123
Net changes in benefit plan assets and obligations									(69)	(307)	39
Net changes in unrealized foreign currency translation and other changes									43	(90)	12
Other comprehensive income before income taxes									336	1,177	56
Income tax expense (benefit)									105	427	20
Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries									231	750	36
Other comprehensive income, net of taxes									231	750	36
Comprehensive income									2,704	2,176	3,252
TPC [Member]
Consolidating financial statements
Net income									1,857	1,182	2,464
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									248	1,100	(77)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									57	(10)	85
Net changes in benefit plan assets and obligations									(6)	(5)	3
Net changes in unrealized foreign currency translation and other changes									(19)	(76)	4
Other comprehensive income before income taxes									280	1,009	15
Income tax expense (benefit)									101	356
Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries									179	653	15
Other comprehensive income, net of taxes									179	653	15
Comprehensive income									2,036	1,835	2,479
Other Subsidiaries [Member]
Consolidating financial statements
Net income									798	382	1,033
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									23	472	(42)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									24	14	38
Net changes in benefit plan assets and obligations									(5)	1	3
Net changes in unrealized foreign currency translation and other changes									62	(14)	8
Other comprehensive income before income taxes									104	473	7
Income tax expense (benefit)									21	177	9
Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries									83	296	(2)
Other comprehensive income, net of taxes									83	296	(2)
Comprehensive income									881	678	1,031
Travelers [Member]
Consolidating financial statements
Net income									2,473	1,426	3,216
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									10	(2)	1
Net changes in benefit plan assets and obligations									(58)	(303)	33
Other comprehensive income before income taxes									(48)	(305)	34
Income tax expense (benefit)									(17)	(106)	11
Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries									(31)	(199)	23
Other comprehensive income of subsidiaries									262	949	13
Other comprehensive income, net of taxes									231	750	36
Comprehensive income									2,704	2,176	3,252
Eliminations [Member]
Consolidating financial statements
Net income									(2,655)	(1,564)	(3,497)
Other comprehensive income of subsidiaries									(262)	(949)	(13)
Other comprehensive income, net of taxes									(262)	(949)	(13)
Comprehensive income									$ (2,917)	$ (2,513)	$ (3,510)