Goodwill and Mortgage Servicing Rights - Mortgage Fees and Related Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Components of mortgage fees and related income [Abstract]
Net production revenue	$ 319	$ 200
Operating revenue:
Loan servicing revenue	339	404
Changes in MSR asset fair value due to collection/realization of expected cash flows	(248)	(199)
Total operating revenue	91	205
Risk management:
Changes in MSR asset fair value due to market interest rates and other	(1,370)	(301)
Other changes in MSR asset fair value due to other inputs and assumptions in model	(12)	2
Change in derivative fair value and other	1,292	290
Total risk management	(90)	(9)
Total net mortgage servicing revenue	1	196
Mortgage fees and related income	$ 320	$ 396