Quarterly report pursuant to Section 13 or 15(d)

Debt (Details)

v3.8.0.1
Debt (Details)
CAD in Millions, AUD in Millions
3 Months Ended
Dec. 31, 2017
USD ($)
period
letter_of_credit
Dec. 31, 2016
USD ($)
Dec. 31, 2017
AUD
period
letter_of_credit
Dec. 31, 2017
CAD
period
letter_of_credit
Credit Agreement Expiring 2022        
Debt Instrument [Line Items]        
Dividend payment restriction ratio (less than) 2.5      
Total leverage ratio (less than) 1.0      
Interest paid $ 100,000 $ 600,000    
Letters of Credit        
Debt Instrument [Line Items]        
Number of letters of credit issued | letter_of_credit 3   3 3
Outstanding borrowings $ 3,100,000      
Letters of Credit (Other than Revolving Credit Agreement)        
Debt Instrument [Line Items]        
Number of letters of credit issued | letter_of_credit 1   1 1
Outstanding borrowings $ 1,000,000      
Atlantic Innovation Fund of Canada        
Debt Instrument [Line Items]        
Amount borrowed $ 600,000     CAD 0.8
Number of remaining quarterly installments | period 18   18 18
Line of Credit | Credit Agreement Expiring 2022        
Debt Instrument [Line Items]        
Amount borrowed $ 10,000,000   AUD 1.6  
Line of Credit | Credit Agreement Expiring 2022 | Revolving Credit Facility        
Debt Instrument [Line Items]        
Maximum borrowing capacity 400,000,000      
Line of Credit | Credit Agreement Expiring 2022 | Bridge Loan        
Debt Instrument [Line Items]        
Maximum borrowing capacity 5,000,000      
Line of Credit | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Maximum borrowing capacity $ 50,000,000      
Minimum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Commitment fee percentage 0.125%      
Maximum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Commitment fee percentage 0.275%      
Base Rate | Minimum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 0.00%      
Base Rate | Maximum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 0.75%      
Eurocurrency Rate | Minimum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 1.00%      
Eurocurrency Rate | Maximum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 1.75%      
Index Rate | Minimum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 1.00%      
Index Rate | Maximum | Credit Agreement Expiring 2022 | Letters of Credit        
Debt Instrument [Line Items]        
Basis spread on variable rate 1.75%