BORROWINGS - Short-Term Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Other Short-term Borrowings	$ 170,000	$ 170,000
Federal Home Loan Bank of Indianapolis Advance, 1.61%, Due January 7, 2020
Short-term Debt [Line Items]
Other Short-term Borrowings	170,000	0
Federal Home Loan Bank of Indianapolis Notes, 2.52%, Due January 7, 2019
Short-term Debt [Line Items]
Other Short-term Borrowings	$ 0	$ 170,000