FINANCIAL INSTRUMENTS - Narrative (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 2,394,446,483	$ 2,249,305,912
Unobservable inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	3,314,363	3,440,809
Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	3,314,363	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	$ 3,314,363	$ 3,440,809