Segment Information (Tables)

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Company's revenues and income by segment [Table Text Block]

(For the three months ended September 30, in millions)	Business Insurance		Bond & Specialty Insurance		Personal Insurance		Total Reportable Segments
2018
Premiums	$	3,743	$	617	$	2,522	$	6,882
Net investment income	482		57		107		646
Fee income	103		—		6		109
Other revenues	33		5		17		55
Total segment revenues (1)	$	4,361	$	679	$	2,652	$	7,692
Segment income (1)	$	410	$	196	$	153	$	759
2017
Premiums	$	3,576	$	591	$	2,356	$	6,523
Net investment income	437		57		94		588
Fee income	108		—		5		113
Other revenues	19		5		14		38
Total segment revenues (1)	$	4,140	$	653	$	2,469	$	7,262
Segment income (1)	$	105	$	136	$	77	$	318

(1) Segment revenues for reportable business segments exclude net realized investment gains (losses). Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses).

(For the nine months ended September 30, in millions)	Business Insurance		Bond & Specialty Insurance		Personal Insurance		Total Reportable Segments
2018
Premiums	$	10,952	$	1,800	$	7,362	$	20,114
Net investment income	1,368		172		304		1,844
Fee income	309		—		15		324
Other revenues	84		16		48		148
Total segment revenues (1)	$	12,713	$	1,988	$	7,729	$	22,430
Segment income (1)	$	1,247	$	573	$	265	$	2,085
2017
Premiums	$	10,509	$	1,721	$	6,827	$	19,057
Net investment income	1,337		174		285		1,796
Fee income	329		—		13		342
Other revenues	43		16		45		104
Total segment revenues (1)	$	12,218	$	1,911	$	7,170	$	21,299
Segment income (1)	$	976	$	444	$	178	$	1,598

(1) Segment revenues for reportable business segments exclude net realized investment gains (losses). Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses).

Business segment reconciliations of revenue and income, net of tax [Table Text Block]

	Three Months Ended September 30,						Nine Months Ended September 30,
(in millions)	2018			2017			2018			2017
Revenue reconciliation
Earned premiums
Business Insurance:
Domestic:
Workers’ compensation	$	988		$	998		$	2,932		$	2,973
Commercial automobile	611			544			1,760			1,571
Commercial property	466			448			1,357			1,326
General liability	558			523			1,614			1,512
Commercial multi-peril	850			806			2,477			2,377
Other	7			7			20			21
Total Domestic	3,480			3,326			10,160			9,780
International	263			250			792			729
Total Business Insurance	3,743			3,576			10,952			10,509
Bond & Specialty Insurance:
Domestic:
Fidelity and surety	261			249			760			728
General liability	255			243			745			717
Other	50			48			146			139
Total Domestic	566			540			1,651			1,584
International	51			51			149			137
Total Bond & Specialty Insurance	617			591			1,800			1,721
Personal Insurance:
Domestic:
Automobile	1,297			1,192			3,783			3,431
Homeowners and Other	1,051			999			3,068			2,931
Total Domestic	2,348			2,191			6,851			6,362
International	174			165			511			465
Total Personal Insurance	2,522			2,356			7,362			6,827
Total earned premiums	6,882			6,523			20,114			19,057
Net investment income	646			588			1,844			1,796
Fee income	109			113			324			342
Other revenues	55			38			148			104
Total segment revenues	7,692			7,262			22,430			21,299
Other revenues	2			2			2			6
Net realized investment gains	29			61			54			146
Total revenues	$	7,723		$	7,325		$	22,486		$	21,451
Income reconciliation, net of tax
Total segment income	$	759		$	318		$	2,085		$	1,598
Interest Expense and Other (1)	(72		)	(65		)	(226		)	(188		)
Core income	687			253			1,859			1,410
Net realized investment gains	22			40			43			95
Net income	$	709		$	293		$	1,902		$	1,505

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(1) The primary component of Interest Expense and Other was after-tax interest expense of $68 million and $61 million in the three months ended September 30, 2018 and 2017, respectively, and $209 million and $179 million in the nine months ended September 30, 2018 and 2017, respectively.

Asset reconciliation [Table Text Block]

(in millions)	September 30, 2018		December 31, 2017
Asset reconciliation
Business Insurance	$	78,665	$	78,082
Bond & Specialty Insurance	9,060		8,776
Personal Insurance	15,955		15,949
Total segment assets	103,680		102,807
Other assets (1)	710		676
Total consolidated assets	$	104,390	$	103,483

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(1) The primary components of other assets at September 30, 2018 were accrued over-funded benefit plan assets related to the Company’s qualified domestic pension plan and other intangible assets, and the primary components at December 31, 2017 were accrued over-funded benefit plan assets related to the Company’s qualified domestic pension plan, other intangible assets and deferred taxes.