Reserve for Known and Incurred but Not Reported Claims - Summary of Incurred and Paid Claims Development Net of Reinsurance (Detail) Claim in Millions, $ in Millions	Dec. 31, 2022 USD ($) Claim	Dec. 31, 2021 USD ($)	[1]	Dec. 31, 2020 USD ($)	[1]	Dec. 31, 2019 USD ($)	[1]	Dec. 31, 2018 USD ($)	[1]	Dec. 31, 2017 USD ($)	[1]	Dec. 31, 2016 USD ($)	[1]	Dec. 31, 2015 USD ($)	[1]	Dec. 31, 2014 USD ($)	[1]	Dec. 31, 2013 USD ($)	[1]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 1,712
Cumulative paid claims and allocated claim adjustment expenses	1,693
All outstanding liabilities before 2013	0
Liabilities for claims and claims adjustment expenses	56
Home warranty
Claims Development [Line Items]
Liabilities for claims and claims adjustment expenses	19
Accident Year 2013 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 124	$ 124		$ 124		$ 124		$ 124		$ 124		$ 124		$ 124		$ 124		$ 124
Cumulative number of reported claims | Claim	0.7
Cumulative paid claims and allocated claim adjustment expenses	$ 124	124		124		124		124		124		124		124		124		$ 111
Accident Year 2014 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 124	124		124		124		124		124		124		124		124
Cumulative number of reported claims | Claim	0.8
Cumulative paid claims and allocated claim adjustment expenses	$ 124	124		124		124		124		124		124		124		$ 111
Accident Year 2015 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 144	144		144		144		144		144		144		144
Cumulative number of reported claims | Claim	0.9
Cumulative paid claims and allocated claim adjustment expenses	$ 144	144		144		144		144		144		144		$ 129
Accident Year 2016 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 173	173		173		173		173		173		173
Cumulative number of reported claims | Claim	1.0
Cumulative paid claims and allocated claim adjustment expenses	$ 173	173		173		173		173		173		$ 155
Accident Year 2017 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 167	167		167		167		167		167
Cumulative number of reported claims | Claim	1.0
Cumulative paid claims and allocated claim adjustment expenses	$ 167	167		167		167		167		$ 151
Accident Year 2018 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 180	180		180		180		180
Cumulative number of reported claims | Claim	1.1
Cumulative paid claims and allocated claim adjustment expenses	$ 180	180		180		180		$ 163
Accident Year 2019 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 174	174		174		174
Cumulative number of reported claims | Claim	1.1
Cumulative paid claims and allocated claim adjustment expenses	$ 174	174		174		$ 159
Accident Year 2020 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 197	197		197
Cumulative number of reported claims | Claim	1.2
Cumulative paid claims and allocated claim adjustment expenses	$ 197	197		$ 178
Accident Year 2021 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 218	218
Cumulative number of reported claims | Claim	1.2
Cumulative paid claims and allocated claim adjustment expenses	$ 218	$ 199
Accident Year 2022 [Member]
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses	$ 211
Cumulative number of reported claims | Claim	1.1
Cumulative paid claims and allocated claim adjustment expenses	$ 192

[1] Amounts unaudited.