FINANCIAL INSTRUMENTS - Narrative (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 2,583,267,939	$ 2,249,305,912
Unobservable inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,993,997	3,440,809
Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,993,997	3,440,809
Mortgage Servicing Rights | Unobservable inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 2,993,997	$ 3,440,809