SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Net Warehouse Interest Income (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Warehouse Interest Income
Net warehouse interest income	$ 6,411	$ 2,392	$ 13,432	$ 4,249
Loans Held for Sale
Net Warehouse Interest Income
Warehouse interest income	12,992	11,382	26,976	20,146
Warehouse interest expense	(12,782)	(9,900)	(26,737)	(17,555)
Net warehouse interest income	210	1,482	239	2,591
Loans Held for Investment
Net Warehouse Interest Income
Warehouse interest income	8,268	1,647	17,047	3,068
Warehouse interest expense	(2,067)	(737)	(3,854)	(1,410)
Net warehouse interest income	6,201	$ 910	13,193	$ 1,658
Secured Borrowings
Net Warehouse Interest Income
Warehouse interest income	920		1,808
Warehouse interest expense	$ (920)		$ (1,808)

Interest and fee income generated by loans the Entity intends and has the ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (1) industrial and agricultural; (2) real estate; and (3) real estate construction loans; (4) trade financing; (5) lease financing; (6) home equity lines-of-credit; (7) automobile and other vehicle loans; and (8) credit card and other revolving-type loans. Also includes interest income for leases held by the Entity.

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-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
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Interest and fee income from mortgage loans considered to be held-for-sale.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The net amount of operating interest income (expense).

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Interest income expense net.

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