FAIR VALUE OF FINANCIAL INSTRUMENTS (Assets and Liabilities Measured at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	$ 2,134,300	$ 1,234,183
Trading Securities, Fair Value	26,981	24,980
Securities—available-for-sale	3,638,993	2,322,593
Securities purchased under agreements to resell	300,000	0
Loans receivable held for sale	96,487	243,795
Loans receivable	9,084,763	9,870,982
FHLB stock	12,000	16,358
Bank-owned life insurance	244,156	191,830
MSRs	16,045	15,223
SBA servicing asset	1,161	0
Investments in limited partnerships	10,257	2,819
Deposits, Demand NOW and Money Market Accounts, Fair Value Disclosure	10,703,586	9,253,494
Deposits, Savings, Fair Value Disclosure	2,784,716	2,398,482
Deposits, Certificates of Deposit, Fair Value Disclosure	838,631	915,320
Advances from FHLB	50,000	150,000
Other borrowings	264,490	184,785
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	119,815	116,974
Reported Value Measurement [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	20,826	39,066
Derivative liabilities	11,336	22,336
Reported Value Measurement [Member] | Interest Rate Swap [Member] | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	279	0
Reported Value Measurement [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,555	5,641
Derivative liabilities	140	1,755
Reported Value Measurement [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Fair Value	464,008	410,038
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Fair Value	57,347	11,769
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	2,134,300	1,234,183
Trading Securities, Fair Value	26,981	24,980
Securities—available-for-sale	3,638,993	2,322,593
Securities purchased under agreements to resell	300,000	0
Loans receivable held for sale	96,914	245,667
Loans receivable	9,100,516	9,810,293
FHLB stock	12,000	16,358
Bank-owned life insurance	244,156	191,830
MSRs	24,393	18,084
SBA servicing asset	1,161	0
Investments in limited partnerships	10,257	2,819
Deposits, Demand NOW and Money Market Accounts, Fair Value Disclosure	10,703,586	9,253,494
Deposits, Savings, Fair Value Disclosure	2,784,716	2,398,482
Deposits, Certificates of Deposit, Fair Value Disclosure	836,877	919,920
Advances from FHLB	50,287	152,779
Other borrowings	264,490	184,785
Subordinated notes, net	105,241	98,201
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	119,815	116,974
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	20,826	39,066
Derivative liabilities	11,336	22,336
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	279	0
Estimate of Fair Value Measurement [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,555	5,641
Derivative liabilities	140	1,755
Estimate of Fair Value Measurement [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Fair Value	484,483	436,882
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Fair Value	57,370	11,799
Trading Securities, Fair Value	26,981	24,980
Securities—available-for-sale	3,638,993	2,322,593
Debt Securities, Held-to-maturity, Fair Value	541,853	448,681
Securities purchased under agreements to resell	300,000	0
Loans receivable held for sale	39,775	133,554
Advances from FHLB	50,000	150,000
Subordinated notes, net	$ 98,564	$ 98,201