SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Contracts with Customers (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Contracts with Customers
Revenue from contracts with customer	$ 33,776	$ 27,908	$ 81,094	$ 63,982
Contract assets with customers	0		0		$ 0
Contract liabilities with customers	0		0		$ 0
Loan Origination Fees \| Gains from Mortgage Banking Activities
Contracts with Customers
Revenue from contracts with customer	18,754	15,981	45,665	39,637
Investment Sales Broker Fees, Investment Management Fees, Assumption Fees, Application Fees and Other \| Other Revenues
Contracts with Customers
Revenue from contracts with customer	$ 15,022	$ 11,927	$ 35,429	$ 24,345

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130533-203044

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Balance Type:	debit
Period Type:	instant