Segment Reporting - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) Segment Client	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | Segment	4
Total assets	$ 89,664	$ 94,903
Business Processing [Member]
Segment Reporting Information [Line Items]
Total assets	$ 431	423
Business Processing [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Number of clients for business processing services | Client	500
Other Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 2,500	$ 1,600