Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Summary of Commercial and Standby Letters of Credit (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Other Commitments [Line Items]
Expires In One Year or Less	$ 2,214,349
Expires After One Year	37,667
Total Amount Outstanding	2,252,016
Maximum Amount of Future Payments	2,252,016
Financial standby letters of credit
Other Commitments [Line Items]
Expires In One Year or Less	2,043,767
Expires After One Year	33,570
Total Amount Outstanding	2,077,337
Maximum Amount of Future Payments	2,077,337
Performance standby letters of credit
Other Commitments [Line Items]
Expires In One Year or Less	133,259
Expires After One Year	3,746
Total Amount Outstanding	137,005
Maximum Amount of Future Payments	137,005
Commercial letters of credit
Other Commitments [Line Items]
Expires In One Year or Less	37,323
Expires After One Year	351
Total Amount Outstanding	37,674
Maximum Amount of Future Payments	$ 37,674