Consolidating Financial Statements (details) - Consolidating Statement of Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Consolidating Statement of Income
Premiums	$ 5,983		$ 5,666		$ 17,734		$ 16,786
Net investment income	719		657		2,150		2,014
Fee income	110		107		329		286
Net realized investment gains (losses)	40.0	[1]	(22.0)	[1]	57.0	[1]	155.0	[1]
Other revenues	34		44		109		213
Total revenues	6,886		6,452		20,379		19,454
Claims and claim adjustment expenses	3,520		3,297		10,661		9,980
Amortization of deferred acquisition costs	984		953		2,899		2,851
General and administrative expenses	1,031		934		2,913		2,780
Interest expense	93		91		277		269
Total claims and expenses	5,628		5,275		16,750		15,880
Income before income taxes	1,258		1,177		3,629		3,574
Income tax expense (benefit)	339		313		975		889
Net income	919		864		2,654		2,685
Total other-than-temporary impairment gains (losses)	(8)		0		(16)		(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)	(10)		(3)		(20)		(10)
Other-than-temporary impairment gains recognized in other comprehensive income	2		3		4		9
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Income
Premiums	4,064		3,839		12,028		11,384
Net investment income	479		438		1,451		1,350
Fee income	110		106		328		284
Net realized investment gains (losses)	(2.0)		3.0		4.0		120.0
Other revenues	28		38		93		170
Total revenues	4,679		4,424		13,904		13,308
Claims and claim adjustment expenses	2,359		2,214		7,149		6,684
Amortization of deferred acquisition costs	642		640		1,927		1,912
General and administrative expenses	716		646		2,026		1,915
Interest expense	12		12		36		41
Total claims and expenses	3,729		3,512		11,138		10,552
Income before income taxes	950		912		2,766		2,756
Income tax expense (benefit)	263		248		770		700
Net income	687		664		1,996		2,056
Total other-than-temporary impairment gains (losses)	(8)		1		(11)		(3)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)	(9)		(2)		(14)		(7)
Other-than-temporary impairment gains recognized in other comprehensive income	1		3		3		4
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Income
Premiums	1,919		1,827		5,706		5,402
Net investment income	239		217		695		659
Fee income			1		1		2
Net realized investment gains (losses)	41.0		(25.0)		50.0		34.0
Other revenues	6		6		16		43
Total revenues	2,205		2,026		6,468		6,140
Claims and claim adjustment expenses	1,161		1,083		3,512		3,296
Amortization of deferred acquisition costs	342		313		972		939
General and administrative expenses	311		286		876		861
Total claims and expenses	1,814		1,682		5,360		5,096
Income before income taxes	391		344		1,108		1,044
Income tax expense (benefit)	106		93		291		269
Net income	285		251		817		775
Total other-than-temporary impairment gains (losses)			(1)		(5)		2
Other-than-temporary impairment losses recognized in net realized investment gains (losses)	(1)		(1)		(6)		(3)
Other-than-temporary impairment gains recognized in other comprehensive income	1				1		5
Reportable Legal Entities [Member] | Travelers [Member]
Consolidating Statement of Income
Net investment income	1		2		4		5
Net realized investment gains (losses)	1.0				3.0		1.0
Total revenues	2		2		7		6
General and administrative expenses	4		2		11		4
Interest expense	81		79		241		228
Total claims and expenses	85		81		252		232
Income before income taxes	(83)		(79)		(245)		(226)
Income tax expense (benefit)	(30)		(28)		(86)		(80)
Net income of subsidiaries	972		915		2,813		2,831
Net income	919		864		2,654		2,685
Eliminations [Member]
Consolidating Statement of Income
Net income of subsidiaries	(972)		(915)		(2,813)		(2,831)
Net income	$ (972)		$ (915)		$ (2,813)		$ (2,831)

[1] Total other-than-temporary impairment (OTTI) gains (losses) were $(8) million and $0 million for the three months ended September 30, 2014 and 2013, respectively, and $(16) million and $(1) million for the nine months ended September 30, 2014 and 2013, respectively. Of total OTTI, credit losses of $(10) million and $(3) million for the three months ended September 30, 2014 and 2013, respectively, and $(20) million and $(10) million for the nine months ended September 30, 2014 and 2013, respectively, were recognized in net realized investment gains (losses). In addition, unrealized gains from other changes in total OTTI of $2 million and $3 million for the three months ended September 30, 2014 and 2013, respectively, and $4 million and $9 million for the nine months ended September 30, 2014 and 2013, 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.