Changes in Deferred Acquisition Costs (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	$ 2,211	$ 2,488
Ending balance	2,150	2,211	$ 2,488
Deferred acquisition costs	2,150	2,211	2,488	$ 2,809
Enact Segment
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	26	27
Ending balance	26	26	27
Deferred acquisition costs	26	26	27
Long-Term Care Insurance
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	935	989	1,043
Costs deferred	0	6	9
Amortization	(14)	(60)	(63)
Ending balance	921	935	989
Deferred acquisition costs	921	935	989
Life Insurance
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	1,080	1,271	1,501
Costs deferred	0	0	0
Amortization	(40)	(191)	(230)
Ending balance	1,040	1,080	1,271
Deferred acquisition costs	1,040	1,080	1,271
Fixed Annuity
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	57	70	85
Costs deferred	0	0	0
Amortization	(3)	(13)	(15)
Ending balance	54	57	70
Deferred acquisition costs	54	57	70
Variable Annuity
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	113	131	151
Costs deferred	0	0	0
Amortization	(4)	(18)	(20)
Ending balance	109	113	131
Deferred acquisition costs	109	113	131
Long-duration insurance contracts
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	2,185	2,461	2,780
Costs deferred	0	6	9
Amortization	(61)	(282)	(328)
Ending balance	2,124	2,185	2,461
Deferred acquisition costs	$ 2,124	$ 2,185	$ 2,461