FAIR VALUE - Summary of assets and liabilities measured at fair value on a recurring or nonrecurring, the significant unobservable inputs (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commercial properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Estimate		$ 194
Commercial and Industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Estimate	$ 479	$ 1,800
Discount | Commercial properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range and weighted average of discount		5.00%
Minimum | Discount rate | Commercial and Industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range and weighted average of discount rate	17.00%	17.00%
Maximum | Discount rate | Commercial and Industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range and weighted average of discount rate	45.00%	35.00%
Weighted Average | Discount | Commercial properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range and weighted average of discount		5.00%
Weighted Average | Discount rate | Commercial and Industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range and weighted average of discount rate	39.00%	26.00%
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset, Fair Value	$ 231	$ 232
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset, Fair Value	231	232
Recurring | Level 3 | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset, Fair Value	$ 231	$ 232
Recurring | Discount rate | Level 3 | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset	3	3
Recurring | Prepayment rate | Level 3 | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset	19	25
Recurring | Weighted Average | Discount rate | Level 3 | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset	3	3
Recurring | Weighted Average | Prepayment rate | Level 3 | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guarantee asset	19	25
Recurring | IRLC,net | Pull through | Level 3 | Best execution model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, Fair Value	$ 2,185	$ 9,841
Recurring | IRLC,net | Minimum | Pull through | Level 3 | Best execution model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	72	55
Recurring | IRLC,net | Maximum | Pull through | Level 3 | Best execution model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	100	100
Recurring | IRLC,net | Weighted Average | Pull through | Level 3 | Best execution model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	90	86
Recurring | Forward Commitment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, Fair Value	$ 481	$ (2,623)
Recurring | Forward Commitment | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, Fair Value	(17)	(89)
Recurring | Forward Commitment | Market Differential | Level 3 | Internal Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, Fair Value	$ (17)	$ (89)
Recurring | Forward Commitment | Minimum | Market Differential | Level 3 | Internal Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0.84	0.59
Recurring | Forward Commitment | Maximum | Market Differential | Level 3 | Internal Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0.50	0.17
Recurring | Forward Commitment | Weighted Average | Market Differential | Level 3 | Internal Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0.75	0.31