Basis of Presentation - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Dilutive securities (in shares)	2	2	2	2
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of applying new accounting standards					$ 200	$ (410)
Retained Earnings | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of applying new accounting standards, pre-tax					265
Cumulative effect of applying new accounting standards					$ 200
Consumer
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Maximum threshold period for new customers			210 days
Minimum threshold period for existing customers			210 days
Business
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Maximum threshold period for new customers			12 months
Minimum threshold period for existing customers			12 months