Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Total	$ 57,550,000,000	$ 19,850,000,000
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2020	12,200,000,000
2021	28,350,000,000
2022	16,000,000,000
2023	500,000,000
2027	500,000,000
Total	$ 57,550,000,000