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CAPITAL SURPLUS AND SHAREHOLDERS DIVIDEND RESTRICTIONS - NARRATIVE (Details) - USD ($) $ in Millions	Feb. 27, 2020	Feb. 20, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			5,000,000	5,000,000.0
Common stock, shares issued (in shares)			2,500,000.0	2,500,000.0
Common stock, shares outstanding (in shares)			2,500,000.0	2,500,000.0
Unassigned surplus (deficit), unrealized gains (losses)			$ (15.4)	$ (21.1)	$ (25.5)
Unassigned Surplus (Deficit)
Class of Stock [Line Items]
Capital contribution		$ 70.0
Subsequent Event \| Unassigned Surplus (Deficit)
Class of Stock [Line Items]
Capital contribution	$ 85.0