BORROWINGS - Short-Term Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Other Short-term Borrowings	$ 75,000	$ 170,000
Federal Home Loan Bank of Indianapolis Advance, 1.61%, Due January 7, 2020
Short-term Debt [Line Items]
Other Short-term Borrowings	0	170,000
Federal Home Loan Bank of Indianapolis Putable Advance, 0.39%, Due March 4, 2030
Short-term Debt [Line Items]
Other Short-term Borrowings	$ 75,000	$ 0