Debt Obligations - Narrative (Details) $ in Thousands, $ in Millions, $ in Millions	Sep. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 CAD ($)	Jun. 30, 2021 AUD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility		$ 323,281			$ 148,508
Senior Credit Facility
Line of Credit Facility [Line Items]
Credit facility available for revolving loans or issuing new letters of credit		1,890,000
Senior Credit Facility | Letters of Credit
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees		301,600
Senior Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowing capacity		$ 2,510,000
2.900% Senior Notes due 2030 | Senior Notes
Line of Credit Facility [Line Items]
Interest rate		2.90%	2.90%	2.90%
Debt instrument		$ 1,000,000
Interest payable on senior notes	$ 14,500
Proceeds from notes offering	$ 986,700
Canadian Dollars | Senior Credit Facility
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility			$ 171.0
Canadian Dollars | Senior Credit Facility | Letters of Credit and Bank Guarantees
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees			$ 91.0
U.S. Dollar | Senior Credit Facility
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility		$ 121,500
Australian Dollars | Senior Credit Facility
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility				$ 30.8