Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters, Summary of Lending Related and Other Commitments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of lending-related and other commitments [Line Items]
Lending related commitments, fair value	$ 0	$ 0
Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale(a)(b)
Summary of lending-related and other commitments
Lending related commitments	10,102,713	10,010,492
Commercial letters of credit(a)
Summary of lending-related and other commitments
Lending related commitments	7,301	3,642
Standby letters of credit(c)
Summary of lending-related and other commitments
Lending related commitments	247,473	$ 278,798
Standby letters of credit, fair value	$ 3,000