Discontinued Operations - Summary of Major Classes of Line Items Constituting Net Income from Discontinued Operations, Net of Tax (Parenthetical) (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (loss) on disposal of Global Connect, net of tax, within discontinued operations				$ 534
Connect
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Debt repayment pursuant to the debt covenants triggered as a result of disposal	$ 1,300
Interest expense allocated to discontinued operations			$ 10	8	$ 28
Disposal group including discontinued operation tax indemnification		$ 9
Gain (loss) on disposal of Global Connect, net of tax, within discontinued operations		$ (8)		$ 534