FAIR VALUE MEASURES - Fair Value Measurements of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value	$ 684,504	$ 982,879
Loans held for sale	1,435,805	1,001,807
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	12,252	17,504
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	54,216	66,778
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value	33,998	51,896
SBA pool securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value	47,917	62,497
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value	536,121	784,204
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	1,435,805	1,001,807
Total recurring assets at fair value	2,145,372	2,036,442
Total recurring liabilities at fair value		16,415
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Total recurring assets at fair value	0	0
Total recurring liabilities at fair value		0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	1,435,805	1,001,807
Total recurring assets at fair value	2,143,992	2,035,272
Total recurring liabilities at fair value		16,415
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	1,380	1,170
Loans held for sale	0	0
Total recurring assets at fair value	1,380	1,170
Total recurring liabilities at fair value		0
Fair Value, Measurements, Recurring | Mortgage banking derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage banking derivative instruments	25,063	51,756
Derivative liability		16,415
Fair Value, Measurements, Recurring | Mortgage banking derivative instruments | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage banking derivative instruments	0	0
Derivative liability		0
Fair Value, Measurements, Recurring | Mortgage banking derivative instruments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage banking derivative instruments	25,063	51,756
Derivative liability		16,415
Fair Value, Measurements, Recurring | Mortgage banking derivative instruments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage banking derivative instruments	0	0
Derivative liability		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	12,252	17,504
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	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	12,252	17,504
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	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	54,216	66,778
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	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	54,216	66,778
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	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	33,998	51,896
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	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	32,618	50,726
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	1,380	1,170
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	47,917	62,497
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	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	47,917	62,497
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	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	536,121	784,204
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	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	536,121	784,204
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	$ 0	$ 0