Description of Business and Basis of Presentation - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) segment	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Number of reportable segments | segment	2
Shareholders' equity	$ 1,688	$ 1,232	$ 831	$ 697	$ 575	$ 656
Increase in long term debt, net	700
Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Shareholders' equity	$ 10,804	$ 10,442	9,656	$ 9,391	$ 9,108	8,594
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncement, Early Adoption [Line Items]
Shareholders' equity			(2)			0
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Shareholders' equity			$ (2)			$ 20