Derivative Instruments - Balance Sheet Offsetting (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Cash collateral
Cash collateral posted in margin accounts	$ 13.9	$ 18.9
Cash collateral received in margin accounts	13.2
Offsetting derivative assets
Gross amount recognized on the balance sheet	120.0	17.9
Gross amount not offset on the balance sheet	(15.2)	(6.9)
Net amount	104.8	11.0
Offsetting derivative liabilities
Gross amount recognized on the balance sheet	15.1	22.1
Gross amount not offset on the balance sheet	(9.2)	(7.7)
Net amount	5.9	14.4
Cash collateral posted	0.4	$ 0.8
Cash collateral received	$ 6.4

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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