Segments of Operations - Revenues by segment and sub-segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
Segment Reporting Information [Line Items]
Total premiums earned	$ 1,209		$ 1,173
Net investment income	544	[1]	542
Other income	57		56
Revenues before realized gains (losses)	1,826		1,840
Realized gains (losses) on securities	(551)		184
Total revenues	1,275		2,024
Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	1,209		1,173
Net investment income	93	[2]	104
Other income	5		3
Revenues before realized gains (losses)	1,307		1,280
Annuity
Segment Reporting Information [Line Items]
Net investment income	422		435
Other income	35		28
Revenues before realized gains (losses)	457		463
Other
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	62		97
Specialty Property and transportation | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	386		361
Specialty casualty | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	556		629
Specialty financial | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	156		146
Other specialty | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	40		37
Other lines | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Total premiums earned	$ 71	[3]	$ 0

[1] Net investment income in the first three months of 2020 includes a loss of $6 million on investments held by the companies that comprise the Neon exited lines due primarily to the $7 million loss recorded on equity securities that are carried at fair value through net investment income.

[2] Includes a net loss of $6 million in the Neon exited lines, primarily from the change in fair value of equity securities.

[3] Represents premiums earned in the Neon exited lines during the first three months of 2020. Neon’s $88 million in earned premiums during the first three months of 2019 are included in the Specialty casualty sub-segment.