PARENT COMPANY STATEMENTS, Condensed Statements of Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents	$ 1,645,805	$ 205,030	$ 211,834	$ 221,038
Investment in and advances to:
Other assets	281,903	243,082
Total assets	13,931,094	11,410,295	10,607,295
Liabilities and shareholders' equity:
Accrued interest and other liabilities	230,724	215,221
Borrowings	77,320	77,320
Shareholders' equity	2,104,107	1,855,234	1,713,783	1,635,315
Total liabilities and shareholders' equity	13,931,094	11,410,295
Parent Company [Member]
Assets:
Cash and cash equivalents	196,021	180,663	$ 116,133	$ 84,460
Investment securities	6,043	2,853
Investment in and advances to:
Bank subsidiary	1,802,150	1,594,790
Non-bank subsidiaries	196,090	180,487
Other assets	15,290	12,406
Total assets	2,215,594	1,971,199
Liabilities and shareholders' equity:
Accrued interest and other liabilities	30,864	24,850
Borrowings	80,623	91,115
Shareholders' equity	2,104,107	1,855,234
Total liabilities and shareholders' equity	$ 2,215,594	$ 1,971,199