Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions |
12 Months Ended | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Apr. 30, 2019 |
Apr. 30, 2018 |
Apr. 30, 2017 |
||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | $ 7,891.1 | $ 6,850.2 | $ 7,008.5 | |||||||||
Reclassification of stranded tax effects | [1] | 0.0 | ||||||||||
Balance | 7,970.5 | 7,891.1 | 6,850.2 | |||||||||
Interest rate contract [Member] | Fair Value Hedging [Member] | Interest Expense [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Gains (losses) reclassified from accumulated other comprehensive loss to earnings (effective portion) | (0.6) | (0.6) | ||||||||||
Interest rate contract [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Gains (losses) reclassified from accumulated other comprehensive loss to earnings (effective portion) | 0.4 | 0.5 | 0.6 | |||||||||
Foreign Currency Translation Adjustment [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | (16.4) | (43.0) | (13.1) | |||||||||
Reclassification adjustments | 0.0 | 0.0 | 0.0 | |||||||||
Current period credit (charge) | (19.1) | 26.6 | (29.9) | |||||||||
Income tax benefit (expense) | 0.0 | 0.0 | 0.0 | |||||||||
Reclassification of stranded tax effects | [2] | 0.0 | ||||||||||
Balance | (35.5) | (16.4) | (43.0) | |||||||||
Unrealized (Loss) Gain on Cash Flow Hedging Derivatives [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | [3] | (2.9) | (4.4) | (4.8) | ||||||||
Reclassification adjustments | [3] | 0.4 | 0.5 | 0.6 | ||||||||
Current period credit (charge) | [3] | (49.1) | 2.7 | 0.0 | ||||||||
Income tax benefit (expense) | [3] | 11.2 | (1.2) | (0.2) | ||||||||
Reclassification of stranded tax effects | [2],[3] | (0.5) | ||||||||||
Balance | [3] | (40.4) | (2.9) | (4.4) | ||||||||
Pension and Other Postretirement Liabilities [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | [4] | (101.0) | (100.0) | (134.1) | ||||||||
Reclassification adjustments | [4] | 7.3 | 10.7 | 13.2 | ||||||||
Current period credit (charge) | [4] | (19.1) | 9.2 | 39.6 | ||||||||
Income tax benefit (expense) | [4] | 2.8 | (5.6) | (18.7) | ||||||||
Reclassification of stranded tax effects | [2],[4] | (15.3) | ||||||||||
Balance | [4] | (110.0) | (101.0) | (100.0) | ||||||||
Unrealized Gain On Available-for-Sale Securities [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | 3.6 | 4.0 | 3.6 | |||||||||
Reclassification adjustments | 0.0 | 0.0 | 0.0 | |||||||||
Current period credit (charge) | 0.7 | (1.7) | 0.6 | |||||||||
Income tax benefit (expense) | (0.2) | 0.5 | (0.2) | |||||||||
Reclassification of stranded tax effects | [2] | 0.8 | ||||||||||
Balance | 4.1 | 3.6 | 4.0 | |||||||||
AOCI Attributable to Parent [Member] | ||||||||||||
AOCI Attributable to Parent, Net of Tax [Roll Forward] | ||||||||||||
Balance | (116.7) | (143.4) | (148.4) | |||||||||
Reclassification adjustments | 7.7 | 11.2 | 13.8 | |||||||||
Current period credit (charge) | (86.6) | 36.8 | 10.3 | |||||||||
Income tax benefit (expense) | 13.8 | (6.3) | (19.1) | |||||||||
Reclassification of stranded tax effects | [1],[2] | (15.0) | ||||||||||
Balance | $ (181.8) | $ (116.7) | $ (143.4) | |||||||||
|