Equity-Based Compensation - Assumptions (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) item $ / shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred income tax benefits included in income tax expense	$ 25	$ 17	$ 37
Employee Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized	75	79	92
Deferred income tax benefits included in income tax expense	17	$ 17	$ 36
Currently unrecognized compensation expense	$ 40
Weighted average period unrecognized compensation expenses expected to be recognized	1 year 6 months
Non-Employee Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of installments | item	2
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock options granted | $ / shares	$ 12.22	$ 12.16	$ 11.71
Expected option life	4 years 2 months 12 days	4 years 3 months 18 days	3 years 6 months
Expected volatility	15.50%	17.90%	15.30%
Expected dividend yield	2.10%	2.20%	2.30%
Risk-free interest rate	2.50%	2.60%	1.70%