Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 19, 2018	Jun. 30, 2017
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	PHII
Entity Registrant Name	PHI INC
Entity Central Index Key	0000350403
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 154,476,608
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		12,897,614