Balance Sheet Offsetting - Disclosure Detail Of Balance Sheet Offsetting Of Financial Assets And Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Customer-related positions
Derivative Assets
Gross Amounts Recognized	$ 91,238	$ 142,643
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	91,238	142,643
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	1,426	48
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	(1)
Net Amount	89,812	142,594
Derivative Liabilities
Gross Amounts Recognized	34,216	43,976
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	34,216	43,976
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	1,426	48
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	32,194	42,552
Net Amount	596	1,376
Interest rate swaps
Derivative Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	0	0
Derivative Liabilities
Gross Amounts Recognized	0	0
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	0	0
Interest rate swaps | Customer-related positions
Derivative Assets
Gross Amounts Recognized	90,748	141,822
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	90,748	141,822
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	1,426	48
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	89,322	141,774
Derivative Liabilities
Gross Amounts Recognized	33,620	42,600
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	33,620	42,600
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	1,426	48
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	32,194	42,552
Net Amount	0	0
Risk participation agreements | Customer-related positions
Derivative Assets
Gross Amounts Recognized	391	722
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	391	722
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	391	722
Derivative Liabilities
Gross Amounts Recognized	530	1,230
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	530	1,230
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	530	1,230
Foreign currency exchange contracts - matched customer book | Customer-related positions
Derivative Assets
Gross Amounts Recognized	81	90
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	81	90
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	(1)
Net Amount	81	89
Derivative Liabilities
Gross Amounts Recognized	61	77
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	61	77
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	61	77
Foreign currency exchange contracts - foreign currency loan
Derivative Assets
Gross Amounts Recognized	18
Gross Amounts Offset in the Statement of Financial Position	0
Net Amounts Presented in the Statement of Financial Position	18
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0
Net Amount	18
Foreign currency exchange contracts - foreign currency loan | Customer-related positions
Derivative Assets
Gross Amounts Recognized		9
Gross Amounts Offset in the Statement of Financial Position		0
Net Amounts Presented in the Statement of Financial Position		9
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments		0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)		0
Net Amount		9
Derivative Liabilities
Gross Amounts Recognized	5	69
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts Presented in the Statement of Financial Position	5	69
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Pledged (Received)	0	0
Net Amount	$ 5	$ 69