Contingencies - Additional Information (Detail) £ in Millions, $ in Millions				3 Months Ended
	Jul. 31, 2016 USD ($)	Jul. 30, 2014 GBP (£)	May 02, 2008 USD ($) helicopter	Jul. 31, 2016 USD ($)	May 05, 2016 Lawsuits	Apr. 30, 2016 Lawsuits
Loss Contingencies [Line Items]
Number of helicopters seized | helicopter			1
Seized value of helicopters			$ 10.0
Contingent fee payment payable	$ 17.2			$ 17.2
Threatened Litigation
Loss Contingencies [Line Items]
Bid recovery costs	$ 23.6	£ 17.8
Foreign tax authority | Secretariat of the Federal Revenue Bureau of Brazil
Loss Contingencies [Line Items]
Additional taxes plus interest and penalties sought by taxing authorities				2.3
Foreign tax authority | Foreign tax authority, Brazilian municipalities
Loss Contingencies [Line Items]
Additional taxes plus interest and penalties sought by taxing authorities				$ 4.8
Rudman et al. v. CHC Group et al
Loss Contingencies [Line Items]
Number of security class action lawsuits pending | Lawsuits					1	2