Borrowings - European Revolving Credit Facility and Term Loan (Details) $ in Thousands		9 Months Ended
	Mar. 27, 2020 USD ($)	Sep. 30, 2020 SEK (kr)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Debt outstanding			$ 2,558,251	$ 2,847,002
European Revolving Credit Facility
Line of Credit Facility [Line Items]
Loan-to-value covenant		45.00%
European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Current borrowing capacity			314,100
Debt Instrument, covenant, interest bearing deposits, maximum | kr		kr 1,200,000,000
European Revolving Credit Facility | Overdraft Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			40,000
Facility line fee		0.125%
Line of Credit | Europe revolving credit
Line of Credit Facility [Line Items]
Debt outstanding			1,025,948	$ 1,017,465
Line of Credit | European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Increase in borrowing capacity	$ 200,000
Debt instrument, additional term	2 years
New lender minimum commitment	$ 100,000
Maximum borrowing capacity			1,300,000
Unused commitment fee		1.23%
Unused line fee as a percentage of margin		35.00%
Current borrowing capacity			$ 118,100
Debt instrument, covenant, maximum GIBD		3.25
Minimum | Line of Credit | European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit, increase limit	50,000
Minimum | Interbank Offered Rate (IBOR) | Line of Credit | European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread variable rate		2.70%
Maximum | Line of Credit | European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit, increase limit	$ 500,000
Maximum | Interbank Offered Rate (IBOR) | Line of Credit | European Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread variable rate		3.80%