Additional Financial Information (Other Assets) (Details) - USD ($) $ in Millions		Mar. 31, 2017	Mar. 31, 2016
Other current assets
Prepaid expenses and other		$ 26.1	$ 26.2
Product inventory		23.9	20.7
Tax credits receivable		145.9	190.0
Other current assets		195.9	236.9
Other non-current assets
Prepaid expenses and other		39.9	31.5
Accounts receivable	[1]	313.1	222.1
Tax credits receivable		119.8	67.1
Other non-current assets		472.8	320.7
Unamortized discount on long-term receivable		$ 17.6	$ 14.0

[1] Unamortized discounts on long-term, non-interest bearing receivables were $17.6 million and $14.0 million at March 31, 2017 and 2016, respectively.