Debt - Credit agreement (Details)		3 Months Ended		6 Months Ended	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Mar. 31, 2020 USD ($) Lender	Jun. 30, 2020	Sep. 30, 2020	Nov. 30, 2020 USD ($)
Line of Credit Facility [Line Items]
Maximum leverage ratio			3.75
Interest coverage ratio			3
Maximum senior secured ratio			2.50
Line of credit | London Interbank Offered Rate (LIBOR) | Minimum | United States of America, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	2.25%
Line of credit | London Interbank Offered Rate (LIBOR) | Maximum | United States of America, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	4.00%
Line of credit | Base rate | Minimum | United States of America, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	1.25%
Line of credit | Base rate | Minimum | Canada, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	1.25%
Line of credit | Base rate | Maximum | United States of America, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Line of credit | Base rate | Maximum | Canada, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Line of credit | Canadian Dealer Offered Rate (CDOR) | Minimum | Canada, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	2.25%
Line of credit | Canadian Dealer Offered Rate (CDOR) | Maximum | Canada, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	4.00%
Line of credit | Bank Bill Swap Bid Rate (BBSY) | Minimum | Australia, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	2.25%
Line of credit | Bank Bill Swap Bid Rate (BBSY) | Maximum | Australia, Dollars
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	4.00%
Credit facility
Line of Credit Facility [Line Items]
Maximum leverage ratio			3.75
Number of lenders | Lender			10
Credit facility | Minimum
Line of Credit Facility [Line Items]
Lender commitments, within credit agreement			$ 24,900,000
Credit facility | Maximum
Line of Credit Facility [Line Items]
Lender commitments, within credit agreement			85,400,000
Credit facility | US term loan
Line of Credit Facility [Line Items]
Term loan, face amount			285,400,000
Revolving credit facility | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			263,500,000
Revolving credit facility, U.S. subsidiaries | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			20,000,000
Outstanding letters of credit			300,000
Revolving credit facility, Canadian subsidiaries | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			183,500,000
Outstanding letters of credit			1,800,000
Revolving credit facility, Australian subsidiaries | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			60,000,000
Outstanding letters of credit			$ 400,000
Maximum Leverage Ratio
Line of Credit Facility [Line Items]
Maximum leverage ratio			4.00
Maximum Leverage Ratio | Revolving credit facility, Australian subsidiaries | Amended And restated syndicated facility agreement
Line of Credit Facility [Line Items]
Gross proceeds from qualified offering of indebtedness			$ 150,000,000
Scenario, Forecast
Line of Credit Facility [Line Items]
Maximum leverage ratio		3.5
Scenario, Forecast | Credit facility
Line of Credit Facility [Line Items]
Maximum leverage ratio		3.50		3.75	3.75
Subsequent Event | First non-extending lender | Credit facility | Canadian term loans
Line of Credit Facility [Line Items]
Canadian term loan						$ 6,000,000
Subsequent Event | Revolving credit facility, Canadian subsidiaries | First non-extending lender | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility						10,000,000
Subsequent Event | Revolving credit facility, Canadian subsidiaries | Second non-extending lender | Credit facility
Line of Credit Facility [Line Items]
Revolving credit facility						$ 14,300,000