Operating expenses (Schedule of Depreciation and Amortization Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses
Depreciation expense	$ 7,746	$ 7,837
Amortization expense	16,479	13,233
Total depreciation and amortization expenses	$ 24,225	$ 21,070