BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2019 reportableSegment subsidiary	Dec. 31, 2020 USD ($) market plan	Dec. 31, 2020 USD ($) market plan segment	Dec. 31, 2020 USD ($) plan reportableSegment market	Dec. 31, 2019 USD ($)		Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Accounting Policies [Line Items]
Number of reportable segments	3		2	2
Cash reserve		$ 0	$ 0	$ 0	$ 3,400,000
Estimated expected credit loss adjustment period		2 years
Straight line reversion period		12 months
Number of stock-based compensation plans | plan		3	3	3
Lease liabilities		$ 112,339,000	$ 112,339,000	$ 112,339,000	117,214,000
Right-of-use assets		97,859,000	97,859,000	97,859,000	102,075,000
Allowance for loan losses		81,238,000	81,238,000	81,238,000	71,982,000			$ 75,312,000	$ 74,742,000
Unfunded loan commitments		6,500,000	6,500,000	6,500,000
Shareholders' equity		$ 868,008,000	$ 868,008,000	$ 868,008,000	819,018,000			753,954,000	785,944,000
Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Allowance for loan losses					(20,385,000)
Unfunded loan commitments					1,400,000
Shareholders' equity					13,492,000	[1]			0	[2]
Leasehold improvements
Accounting Policies [Line Items]
Property plant and equipment useful life		10 years
Buildings
Accounting Policies [Line Items]
Property plant and equipment useful life		40 years
Furniture and Fixtures
Accounting Policies [Line Items]
Property plant and equipment useful life		6 years
Office Equipment
Accounting Policies [Line Items]
Property plant and equipment useful life		5 years
Computer Equipment
Accounting Policies [Line Items]
Property plant and equipment useful life		3 years
Minimum
Accounting Policies [Line Items]
Finite-lived intangible asset useful life		8 years
Award vesting period		1 year
Maximum
Accounting Policies [Line Items]
Finite-lived intangible asset useful life		15 years
Award vesting period		5 years
Private Banking
Accounting Policies [Line Items]
Number of geographic markets | market		3	3	3
Affiliate Partners Segment
Accounting Policies [Line Items]
Number of subsidiaries | subsidiary	2
Accounting Standards Update 2016-02
Accounting Policies [Line Items]
Lease liabilities							$ 124,100,000
Right-of-use assets							$ 108,500,000
Residential
Accounting Policies [Line Items]
Amount eligible for purchase by FNMA, general limit		$ 510,000	$ 510,000	$ 510,000
Amount eligible for purchase by FNMA, high cost limit		766,000	766,000	766,000
Allowance for loan losses		$ 12,864,000	$ 12,864,000	$ 12,864,000	8,857,000			$ 10,026,000	$ 9,773,000
Residential | Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Allowance for loan losses					$ 685,000

[1] Impact due to the adoption of ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) (“ASU 2016-13”). See Part II. Item 8. “Financial Statements and Supplementary Data - Note 1: Basis of Presentation and Summary of Significant Accounting Policies.”

[2] Impact due to the adoption of Accounting Standards Update ("ASU") 2016-01, Recognition and Measurements of Financial Assets and Financial Liabilities ("ASU 2016-01") and ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). See Part II. Item 8. “Financial Statements and Supplementary Data - Note 1: Basis of Presentation and Summary of Significant Accounting Policies” in the Company's Annual Report on Form 10-K for the year ended December 31, 2019.