Occupancy Expense and Information Systems and Communications Expense - Summary of Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Leases
2020	$ 183
2021	180
2022	164
2023	143
2024	108
Thereafter	356
Total future minimum lease payments	1,134
Less imputed interest	(114)
Total	1,020
Finance Leases
2020	41
2021	41
2022	41
2023	31
2024	0
Thereafter	0
Total future minimum lease payments	154
Less imputed interest	(18)
Total	136	$ 190
2020	224
2021	221
2022	205
2023	174
2024	108
Thereafter	356
Total future minimum lease payments	1,288
Less imputed interest	(132)
Total	$ 1,156