Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Trading Symbol	PHII
Entity Registrant Name	PHI INC
Entity Central Index Key	0000350403
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Voting Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		2,905,757
Non-Voting Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		12,893,895