Description of Business and Basis of Presentation - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) segment	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Number of reportable segments | segment	2
Shareholders' equity	$ 1,232	$ 799	$ 831	$ 575	$ 325	$ 656
3.75% 2020 Senior Notes, due 2025
New Accounting Pronouncement, Early Adoption [Line Items]
Increase in long term debt, net	700
Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Shareholders' equity	$ 10,442	$ 10,041	9,656	$ 9,108	$ 8,893	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