INDEBTEDNESS - Summary of Credit Facilities (Details) - Credit Agreement - Revolving Credit Facility - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Commitments	$ 400,000,000.0	$ 400,000,000.0
Outstanding Borrowings	138,500,000	134,500,000
Letter of Credit Outstanding	5,100,000	5,200,000
Borrowing Capacity	$ 256,400,000	$ 260,300,000