Segment Information (Purchase Accounting and Related Adjustments) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Corporate and reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting and related adjustments	$ 153.7	$ 195.5	$ 194.0
Direct operating | Corporate and reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting and related adjustments	0.0	0.7	0.4
General and administrative expense
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting and related adjustments	11.6	54.7
General and administrative expense | Corporate and reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting and related adjustments	11.6	54.7	58.7
Amortization of recoupable portion of the purchase price	1.3	7.7	7.7
Noncontrolling interest discount amortization	0.0	13.2	22.7
Noncontrolling equity interest in distributable earnings	10.3	33.8	28.3
Depreciation and amortization expense | Corporate and reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting and related adjustments	$ 142.1	$ 140.1	$ 134.9