FAIR VALUE OF FINANCIAL INSTRUMENTS (Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	$ 21,040	$ 25,636
Securities—available-for-sale	1,608,224	1,551,557
Advances from FHLB	247,000	450,000
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,608,224	1,551,557
Total assets	1,844,515	1,792,900
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	99,795	119,304
Total liabilities	127,523	130,944
Recurring [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3,325	15,202
Derivative liabilities	4,448	10,966
Recurring [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42,687	1,108
Derivative liabilities	23,280	674
Recurring [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	81,763	89,598
Recurring [Member] | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	181,039	107,157
Recurring [Member] | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	30,986	4,365
Recurring [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	21,040	25,636
Recurring [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,306,799	1,342,311
Recurring [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	7,637	8,126
Recurring [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	169,239	199,397
Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI		0
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Total assets	0	0
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	0	0
Total liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Recurring [Member] | Level 1 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	0	0
Recurring [Member] | Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI		0
Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,608,224	1,551,557
Total assets	1,820,958	1,766,473
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	0	0
Total liabilities	27,728	11,640
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	808	15,202
Derivative liabilities	4,448	10,966
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42,687	317
Derivative liabilities	23,280	674
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	81,763	89,598
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	181,039	107,157
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	30,986	4,365
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,306,799	1,342,311
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	7,637	8,126
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	169,239	199,397
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI		0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Total assets	23,557	26,427
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	99,795	119,304
Total liabilities	99,795	119,304
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,517	0
Derivative liabilities	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	791
Derivative liabilities	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	21,040	25,636
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI		$ 0