SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Contracts with Customers (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Contracts with Customers
Revenue from contracts with customer	$ 20,463	$ 17,857	$ 36,073	$ 32,870
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	12,371	13,380	23,656	23,452
Investment Sales Broker Fees, Assumption Fees, Application Fees, and Other | Other
Contracts with Customers
Revenue from contracts with customer	$ 8,092	$ 4,477	$ 12,417	$ 9,418