DERIVATIVE INSTRUMENTS - BALANCE SHEET OFFSETTING (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Cash collateral
Cash collateral posted in margin accounts	$ 4.0	$ 6.7
Cash collateral received in margin accounts	16.7
Offsetting derivative assets
Gross amount recognized on the balance sheet	33.2	6.3
Gross amount not offset on the balance sheet	(16.7)	(2.9)
Net amount	16.5	3.4
Cash collateral received	16.7
Offsetting derivative liabilities
Gross amount recognized on the balance sheet	0.4	4.1
Gross amount not offset on the balance sheet	0.0	(2.9)
Net amount	$ 0.4	$ 1.2

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