Goodwill and Intangibles - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2008
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill allocated		$ 2,709	$ 2,709	$ 2,709	$ 3,500
Impairment loss recognized		2,709	$ 2,102	$ 2,102	$ 2,700
Goodwill impairment loss	$ 607	$ 607