Equity Securities (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule Of Investments [Line Items]
Net (losses) gains on equity securities	$ (65)	$ 19
Net unrealized gains and (losses) on equity securities	(65)	18
Cash proceeds from sale of equity securities	83	68
Non Marketable Equity Securities
Schedule Of Investments [Line Items]
Net unrealized gains and (losses) on equity securities	(11)	$ 42
Realized gain on securities	51
Non Marketable Equity Securities | Offerpad Inc [Member]
Schedule Of Investments [Line Items]
Net unrealized losses on equity securities	44
Non Marketable Equity Securities | Tech-enabled real estate company
Schedule Of Investments [Line Items]
Net unrealized losses on equity securities	11
Investment In Insurance Business
Schedule Of Investments [Line Items]
Cash proceeds from sale of equity securities	$ 63