Guarantor Subsidiaries - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Cash provided by operating activities	$ 258.1	$ 228.5	$ 195.1
Investing activities
Expenditures for property, plant and equipment	(44.9)	(40.7)	(54.5)
Acquisitions, net of cash acquired	(23.4)	(173.6)	(213.7)
Proceeds from dispositions of long-lived assets	4.7	5.5	4.2
Cash dividend from equity method investment	1.3	0.0	0.0
Net proceeds from divestiture of discontinued operations	9.0	0.0	0.0
Cash used for investing activities	(53.3)	(208.8)	(264.0)
Financing activities
Proceeds from borrowings of debt	270.8	1,529.8	1,606.4
Repayments of debt	(369.0)	(1,816.2)	(1,905.3)
Payment of debt issuance costs	0.0	(11.0)	(11.8)
Deferred acquisition payment	0.0	0.0	(5.7)
Payment of preferred stock dividends	(23.2)	(23.2)	(4.4)
Proceeds from exercise of stock options	7.9	7.2	11.0
Proceeds from issuance of preferred stock, net of direct offering costs	0.0	0.0	389.7
Taxes withheld and paid on employees' share-based payment awards	(3.2)	(1.2)	0.0
Proceeds from financing lease obligations	0.0	5.8	0.0
Cash (used for) provided by financing activities	(116.7)	(308.8)	79.9
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(13.2)	16.6	(5.5)
Increase (decrease) in cash, cash equivalents and restricted cash	74.9	(272.5)	5.5
Cash, cash equivalents and restricted cash at beginning of period	217.6	490.1	484.6
Cash, cash equivalents and restricted cash at end of period	292.5	217.6	490.1
Eliminations
Operating activities
Cash provided by operating activities	0.0	0.0	0.0
Investing activities
Expenditures for property, plant and equipment	0.0	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0	0.0
Proceeds from dispositions of long-lived assets	0.0	0.0	0.0
Cash dividend from equity method investment	0.0
Net proceeds from divestiture of discontinued operations	0.0
Cash used for investing activities	0.0	0.0	0.0
Financing activities
Proceeds from borrowings of debt	0.0	0.0	0.0
Repayments of debt	0.0	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Deferred acquisition payment			0.0
Payment of preferred stock dividends	0.0	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0	0.0
Proceeds from issuance of preferred stock, net of direct offering costs			0.0
Taxes withheld and paid on employees' share-based payment awards	0.0	0.0
Proceeds from financing lease obligations		0.0
Cash (used for) provided by financing activities	0.0	0.0	0.0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	0.0	0.0	0.0
Cash, cash equivalents and restricted cash at beginning of period	0.0	0.0	0.0
Cash, cash equivalents and restricted cash at end of period	0.0	0.0	0.0
Parent
Operating activities
Cash provided by operating activities	19.9	12.3	(397.5)
Investing activities
Expenditures for property, plant and equipment	0.0	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0	0.0
Proceeds from dispositions of long-lived assets	0.0	0.0	0.0
Cash dividend from equity method investment	0.0
Net proceeds from divestiture of discontinued operations	0.0
Cash used for investing activities	0.0	0.0	0.0
Financing activities
Proceeds from borrowings of debt	0.0	0.0	0.0
Repayments of debt	0.0	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Deferred acquisition payment			0.0
Payment of preferred stock dividends	(23.2)	(23.2)	(4.4)
Proceeds from exercise of stock options	7.9	7.2	11.0
Proceeds from issuance of preferred stock, net of direct offering costs			389.7
Taxes withheld and paid on employees' share-based payment awards	(3.2)	(1.2)
Proceeds from financing lease obligations		0.0
Cash (used for) provided by financing activities	(18.5)	(17.2)	396.3
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	1.4	(4.9)	(1.2)
Cash, cash equivalents and restricted cash at beginning of period	0.0	4.9	6.1
Cash, cash equivalents and restricted cash at end of period	1.4	0.0	4.9
Issuers
Operating activities
Cash provided by operating activities	75.2	313.4	308.8
Investing activities
Expenditures for property, plant and equipment	0.0	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0	0.0
Proceeds from dispositions of long-lived assets	0.0	0.0	0.0
Cash dividend from equity method investment	0.0
Net proceeds from divestiture of discontinued operations	0.0
Cash used for investing activities	0.0	0.0	0.0
Financing activities
Proceeds from borrowings of debt	0.0	1,324.0	1,606.4
Repayments of debt	(75.0)	(1,626.5)	(1,905.3)
Payment of debt issuance costs		(11.0)	(11.8)
Deferred acquisition payment			0.0
Payment of preferred stock dividends	0.0	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0	0.0
Proceeds from issuance of preferred stock, net of direct offering costs			0.0
Taxes withheld and paid on employees' share-based payment awards	0.0	0.0
Proceeds from financing lease obligations		0.0
Cash (used for) provided by financing activities	(75.0)	(313.5)	(310.7)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	0.2	(0.1)	(1.9)
Cash, cash equivalents and restricted cash at beginning of period	0.0	0.1	2.0
Cash, cash equivalents and restricted cash at end of period	0.2	0.0	0.1
Guarantor Subsidiaries
Operating activities
Cash provided by operating activities	112.9	(161.2)	215.7
Investing activities
Expenditures for property, plant and equipment	(33.0)	(28.4)	(43.3)
Acquisitions, net of cash acquired	(2.0)	(50.0)	(213.4)
Proceeds from dispositions of long-lived assets	4.7	5.3	4.2
Cash dividend from equity method investment	0.0
Net proceeds from divestiture of discontinued operations	3.0
Cash used for investing activities	(27.3)	(73.1)	(252.5)
Financing activities
Proceeds from borrowings of debt	268.0	205.8	0.0
Repayments of debt	(286.8)	(189.7)	0.0
Payment of debt issuance costs		0.0	0.0
Deferred acquisition payment			0.0
Payment of preferred stock dividends	0.0	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0	0.0
Proceeds from issuance of preferred stock, net of direct offering costs			0.0
Taxes withheld and paid on employees' share-based payment awards	0.0	0.0
Proceeds from financing lease obligations		5.8
Cash (used for) provided by financing activities	(18.8)	21.9	0.0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	66.8	(212.4)	(36.8)
Cash, cash equivalents and restricted cash at beginning of period	40.9	253.3	290.1
Cash, cash equivalents and restricted cash at end of period	107.7	40.9	253.3
Non-Guarantor Subsidiaries
Operating activities
Cash provided by operating activities	50.1	64.0	68.1
Investing activities
Expenditures for property, plant and equipment	(11.9)	(12.3)	(11.2)
Acquisitions, net of cash acquired	(21.4)	(123.6)	(0.3)
Proceeds from dispositions of long-lived assets	0.0	0.2	0.0
Cash dividend from equity method investment	1.3
Net proceeds from divestiture of discontinued operations	6.0
Cash used for investing activities	(26.0)	(135.7)	(11.5)
Financing activities
Proceeds from borrowings of debt	2.8	0.0	0.0
Repayments of debt	(7.2)	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Deferred acquisition payment			(5.7)
Payment of preferred stock dividends	0.0	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0	0.0
Proceeds from issuance of preferred stock, net of direct offering costs			0.0
Taxes withheld and paid on employees' share-based payment awards	0.0	0.0
Proceeds from financing lease obligations		0.0
Cash (used for) provided by financing activities	(4.4)	0.0	(5.7)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(13.2)	16.6	(5.5)
Increase (decrease) in cash, cash equivalents and restricted cash	6.5	(55.1)	45.4
Cash, cash equivalents and restricted cash at beginning of period	176.7	231.8	186.4
Cash, cash equivalents and restricted cash at end of period	$ 183.2	$ 176.7	$ 231.8