Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Summary of Commercial and Standby Letters of Credit (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Expires In One Year or Less	$ 2,815,878
Expires After One Year	94,040
Total Amount Outstanding	2,909,918	$ 2,778,561
Maximum Amount of Future Payments	2,909,918
Financial standby letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	2,701,150
Expires After One Year	76,538
Total Amount Outstanding	2,777,688
Maximum Amount of Future Payments	2,777,688
Performance standby letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	105,359
Expires After One Year	17,406
Total Amount Outstanding	122,765
Maximum Amount of Future Payments	122,765
Commercial letters of credit
Guarantor Obligations [Line Items]
Expires In One Year or Less	9,369
Expires After One Year	96
Total Amount Outstanding	9,465
Maximum Amount of Future Payments	$ 9,465