Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Summary of Commercial and Standby Letters of Credit (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Expires In One Year or Less	$ 2,835,746
Expires After One Year	98,150
Total Amount Outstanding	2,933,896	$ 2,778,561
Maximum Amount of Future Payments	2,933,896
Financial standby letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	2,723,597
Expires After One Year	80,267
Total Amount Outstanding	2,803,864
Maximum Amount of Future Payments	2,803,864
Performance standby letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	109,279
Expires After One Year	17,787
Total Amount Outstanding	127,066
Maximum Amount of Future Payments	127,066
Commercial letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	2,870
Expires After One Year	96
Total Amount Outstanding	2,966
Maximum Amount of Future Payments	$ 2,966