FAIR VALUE MEASURES - Fair Value Measurements of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	$ 982,879	$ 1,403,403
Loans held for sale, fair value	1,001,807	1,656,711
U.S. government sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	17,504	22,362
State, county and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	66,778	105,260
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	51,896	52,999
SBA pool securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	62,497	73,912
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	784,204	1,148,870
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, fair value	1,001,807	1,656,711
Total recurring assets at fair value	2,036,442	3,067,928
Total recurring liabilities at fair value	16,415	4,658
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, fair value	0	0
Total recurring assets at fair value	0	0
Total recurring liabilities at fair value	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, fair value	1,001,807	1,656,711
Total recurring assets at fair value	2,035,272	3,066,428
Total recurring liabilities at fair value	16,415	4,658
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	1,170	1,500
Loans held for sale, fair value	0	0
Total recurring assets at fair value	1,170	1,500
Total recurring liabilities at fair value	0	0
Fair Value, Measurements, Recurring | U.S. government sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	17,504	22,362
Fair Value, Measurements, Recurring | U.S. government sponsored agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | U.S. government sponsored agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	17,504	22,362
Fair Value, Measurements, Recurring | U.S. government sponsored agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | State, county and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	66,778	105,260
Fair Value, Measurements, Recurring | State, county and municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | State, county and municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	66,778	105,260
Fair Value, Measurements, Recurring | State, county and municipal securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	51,896	52,999
Fair Value, Measurements, Recurring | Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	50,726	51,499
Fair Value, Measurements, Recurring | Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	1,170	1,500
Fair Value, Measurements, Recurring | SBA pool securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	62,497	73,912
Fair Value, Measurements, Recurring | SBA pool securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | SBA pool securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	62,497	73,912
Fair Value, Measurements, Recurring | SBA pool securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	784,204	1,148,870
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	784,204	1,148,870
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value, net of allowance for credit losses of $112 and $0	0	0
Derivative financial instruments | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		187
Derivative financial instruments | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		0
Derivative financial instruments | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		187
Derivative financial instruments | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		0
Mortgage banking derivative instruments | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	51,756	7,814
Derivative liability	16,415	4,471
Mortgage banking derivative instruments | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Mortgage banking derivative instruments | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	51,756	7,814
Derivative liability	16,415	4,471
Mortgage banking derivative instruments | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	$ 0	$ 0