Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 98	$ 234
Other comprehensive income (loss), net of tax:
Unrealized losses on debt securities	(371)	(100)
Foreign currency translation adjustment	1	3
Pension benefit adjustment	1	1
Total other comprehensive loss, net of tax	(369)	(96)
Comprehensive (loss) income	$ (271)	$ 138