Income Taxes Income Tax Examinations (Details) $ in Millions |
Apr. 30, 2017
USD ($)
|
|---|---|
| Unrecognized Deferred Tax [Abstract] | |
| Temporary difference on indefinitely reinvested undistributed earnings of the Company's Canadian, UK, Australian and Japanese subsidiaries | $ 54.2 |
| Unrecognized deferred income tax liability related to the temporary difference on indefinitely reinvested undistributed earnings of Company's Canadian, UK, Australian and Japanese subsidiaries | $ 6.7 |