Fair Value of Financial Instruments (Tables)

12 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

The following table shows the carrying amounts and fair values of the Company’s senior and junior subordinated convertible debt as of March 31, 2018 and 2017 (amounts in millions). As of March 31, 2018 and March 31, 2017, the carrying amounts of the Company's senior and junior subordinated convertible debt have been reduced by debt issuance costs of $34.2 million and $38.3 million, respectively.

	March 31,
	2018				2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
2017 Senior Debt	$	1,437.6	$	2,459.2	$	1,384.9	$	2,106.2
2015 Senior Debt	$	1,309.9	$	3,079.1	$	1,261.8	$	2,481.7
2017 Junior Debt	$	326.7	$	876.9	$	262.3	$	586.6
2007 Junior Debt	$	—	$	—	$	50.0	$	445.1