Business Developments And Risks And Uncertainties (Narrative) (Detail) $ in Millions				9 Months Ended
	Jul. 01, 2022 USD ($)	Mar. 15, 2022 USD ($)	Jan. 01, 2022 USD ($)	Sep. 30, 2022 USD ($) segments	Nov. 30, 2022 USD ($)	Jul. 08, 2022 USD ($)
Business Acquisition [Line Items]
Number of operating segments | segments				3
Gain loss on assets and liabilities reclassified as held for sale				$ 0
GO PSA [Member]
Business Acquisition [Line Items]
Proceeds from GO PSA		$ 1,000
National Public Finance Guarantee Corporation [Member] | GO PSA [Member]
Business Acquisition [Line Items]
Conditional value instrument additional recoveries from the percentage of sales and usage tax receipts				5.50%
Acceleration and commutation payment				$ 277
National Public Finance Guarantee Corporation [Member] | Puerto Rico Highway and Transportation Authority [Member]
Business Acquisition [Line Items]
Cash						$ 33
Contingent value instrument						$ 358
Subsequent Event [Member] | National Public Finance Guarantee Corporation [Member] | Puerto Rico Highway and Transportation Authority [Member]
Business Acquisition [Line Items]
Cash					$ 45
Contingent value instrument					$ 133
Maximum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member]
Business Acquisition [Line Items]
Outstanding bonds				0
Maximum [Member] | GO And PBA Bonds [Member] | National Public Finance Guarantee Corporation [Member]
Business Acquisition [Line Items]
Gross par outstanding				0
Minimum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member]
Business Acquisition [Line Items]
Outstanding bonds				495
Gross par outstanding				380
Puerto Rico [Member]
Business Acquisition [Line Items]
Claims payments			$ 47
Outstanding bonds				$ 2,000
Puerto Rico [Member] | National Public Finance Guarantee Corporation [Member]
Business Acquisition [Line Items]
Claims payments	$ 142