INDEBTEDNESS - Schedule of Credit Facility (Details) - Credit Agreement - Revolving Credit Facility - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Commitments	$ 400,000,000.0	$ 400,000,000.0
Outstanding Borrowings	148,500,000	134,500,000
Letters of Credit Outstanding	5,100,000	5,200,000
Borrowing Capacity	$ 246,400,000	$ 260,300,000