PARENT COMPANY STATEMENTS - Condensed Statements of Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Cash and cash equivalents	$ 190,962	$ 209,896
Investment in and advances to:
Other assets	435,611	446,304
Total assets	15,555,753	15,835,651	$ 15,552,657
Liabilities and shareholders' equity:
Accrued interest and other liabilities	164,497	133,863
Shareholders' equity	1,697,937	1,551,705	$ 2,100,807	$ 2,104,107
Total liabilities and shareholders' equity	15,555,753	15,835,651
Parent Company
Assets:
Cash and cash equivalents	134,023	160,045
Investment securities	10,352	7,881
Investment in and advances to:
Bank subsidiary	1,341,146	1,194,314
Non-bank subsidiaries	226,202	207,172
Other assets	20,765	17,106
Total assets	1,732,488	1,586,518
Liabilities and shareholders' equity:
Accrued interest and other liabilities	34,551	31,564
Borrowings	0	3,249
Shareholders' equity	1,697,937	1,551,705
Total liabilities and shareholders' equity	$ 1,732,488	$ 1,586,518