Consolidating Financial Statements (details) - Consolidating Statement of Income (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Consolidating Statement of Income
Premiums		$ 6,032	$ 5,983	$ 17,851	$ 17,734
Net investment income		614	719	1,838	2,150
Fee income		112	110	334	329
Net realized investment gains (losses)	[1]	15	40	35	57
Other revenues		21	34	68	109
Total revenues		6,794	6,886	20,126	20,379
Claims and claim adjustment expenses		3,382	3,520	10,360	10,661
Amortization of deferred acquisition costs		987	984	2,913	2,899
General and administrative expenses		1,024	1,031	3,044	2,913
Interest expense		94	93	278	277
Total claims and expenses		5,487	5,628	16,595	16,750
Income before income taxes		1,307	1,258	3,531	3,629
Income tax expense (benefit)		379	339	958	975
Net income		928	919	2,573	2,654
Total other-than-temporary impairment losses		(14)	(8)	(26)	(16)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)		(14)	(10)	(23)	(20)
Other-than-temporary impairment gains (losses) recognized in OCI		0	2	(3)	4
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Income
Premiums		4,110	4,064	12,150	12,028
Net investment income		400	479	1,235	1,451
Fee income		112	110	334	328
Net realized investment gains (losses)		5	(2)	24	4
Other revenues		15	28	55	93
Total revenues		4,642	4,679	13,798	13,904
Claims and claim adjustment expenses		2,264	2,359	6,982	7,149
Amortization of deferred acquisition costs		663	642	1,956	1,927
General and administrative expenses		711	716	2,123	2,026
Interest expense		12	12	36	36
Total claims and expenses		3,650	3,729	11,097	11,138
Income before income taxes		992	950	2,701	2,766
Income tax expense (benefit)		293	263	742	770
Net income		699	687	1,959	1,996
Total other-than-temporary impairment losses		(5)	(8)	(13)	(11)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)		(5)	(9)	(11)	(14)
Other-than-temporary impairment gains (losses) recognized in OCI			1	(2)	3
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Income
Premiums		1,922	1,919	5,701	5,706
Net investment income		213	239	599	695
Fee income					1
Net realized investment gains (losses)		10	41	10	50
Other revenues		6	6	13	16
Total revenues		2,151	2,205	6,323	6,468
Claims and claim adjustment expenses		1,118	1,161	3,378	3,512
Amortization of deferred acquisition costs		324	342	957	972
General and administrative expenses		309	311	909	876
Total claims and expenses		1,751	1,814	5,244	5,360
Income before income taxes		400	391	1,079	1,108
Income tax expense (benefit)		113	106	292	291
Net income		287	285	787	817
Total other-than-temporary impairment losses		(9)		(13)	(5)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)		(9)	(1)	(12)	(6)
Other-than-temporary impairment gains (losses) recognized in OCI			1	(1)	1
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Income
Net investment income		1	1	4	4
Net realized investment gains (losses)			1	1	3
Total revenues		1	2	5	7
General and administrative expenses		4	4	12	11
Interest expense		82	81	242	241
Total claims and expenses		86	85	254	252
Income before income taxes		(85)	(83)	(249)	(245)
Income tax expense (benefit)		(27)	(30)	(76)	(86)
Net income of subsidiaries		986	972	2,746	2,813
Net income		928	919	2,573	2,654
Eliminations [Member]
Consolidating Statement of Income
Net income of subsidiaries		(986)	(972)	(2,746)	(2,813)
Net income		$ (986)	$ (972)	$ (2,746)	$ (2,813)

[1] Total other-than-temporary impairment (OTTI) losses were $(14) million and $(8) million for the three months ended September 30, 2015 and 2014, respectively, and $(26) million and $(16) million for the nine months ended September 30, 2015 and 2014, respectively. Of total OTTI, credit losses of $(14) million and $(10) million for the three months ended September 30, 2015 and 2014, respectively, and $(23) million and $(20) million for the nine months ended September 30, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $0 million and $2 million for the three months ended September 30, 2015 and 2014, respectively, and $(3) million and $4 million for the nine months ended September 30, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.