Fair value measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Short-term investments available for sale:
Available-for-sale	$ 0	$ 59,923
Other assets
Derivatives	10,453	6,124
Total Assets	124,006	211,513
Derivatives	(7,528)	(19,359)
Total Liabilities	(7,528)	$ (19,359)
Available-for-sale contractual maturity (in months)		60 months
Level 1
Other assets
Derivatives	0	$ 0
Total Assets	113,553	145,466
Derivatives	0	0
Total Liabilities	0	0
Level 2
Other assets
Derivatives	10,453	6,124
Total Assets	10,453	66,047
Derivatives	(7,528)	(19,359)
Total Liabilities	(7,528)	(19,359)
Level 3
Other assets
Derivatives	0	0
Total Assets	0	0
Derivatives	0	0
Total Liabilities	0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	113,553	145,466
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	113,553	145,466
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0	0
Corporate bonds
Short-term investments available for sale:
Available-for-sale		59,923
Corporate bonds | Level 1
Short-term investments available for sale:
Available-for-sale		0
Corporate bonds | Level 2
Short-term investments available for sale:
Available-for-sale		59,923
Corporate bonds | Level 3
Short-term investments available for sale:
Available-for-sale		$ 0