Commitments and Contingencies (Credit-Related Commitments) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Loan commitments
Commitments to Extend Credit
Expire in One Year or Less	$ 3,090,244
Expire After One Year Through Three Years	1,943,216
Expire After Three Years Through Five Years	638,815
Expire After Five Years	172,171
Total	5,844,446	$ 5,690,917
Commercial letters of credit and SBLCs
Commitments to Extend Credit
Expire in One Year or Less	1,263,991
Expire After One Year Through Three Years	398,670
Expire After Three Years Through Five Years	166,496
Expire After Five Years	513,202
Total	2,342,359	2,240,813
Commitments to Extend Credit
Commitments to Extend Credit
Expire in One Year or Less	4,354,235
Expire After One Year Through Three Years	2,341,886
Expire After Three Years Through Five Years	805,311
Expire After Five Years	685,373
Total	$ 8,186,805	$ 7,931,730