Operations and summary of significant accounting policies - Schedule of Effect From Topic 842 (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, net	$ 243,717		$ 245,201
Operating lease right-of-use assets	70,407	$ 52,000
Total Assets	1,651,889		1,671,235
Operating lease liabilities, current	13,431
Operating lease liabilities, non-current	40,650
Other current liabilities				$ 25,882
Total Liabilities and Stockholders' Equity	$ 1,651,889		1,671,235
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, net		226,595
Operating lease right-of-use assets		68,938
Total Assets		295,533
Operating lease liabilities, current		18,597
Operating lease liabilities, non-current		33,853
Other current liabilities		23,795
Total Liabilities and Stockholders' Equity		76,245
Total Assets less Total Liabilities and Stockholders' Equity		219,288
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, net			245,201
Total Assets			245,201
Other current liabilities			25,913
Total Liabilities and Stockholders' Equity			25,913
Total Assets less Total Liabilities and Stockholders' Equity			$ 219,288
Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities, current		18,597
Operating lease liabilities, non-current		33,853
Restatement Adjustment | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, net		(18,606)
Operating lease right-of-use assets		68,938
Total Assets		50,332
Other current liabilities		(2,118)
Total Liabilities and Stockholders' Equity		50,332
Total Assets less Total Liabilities and Stockholders' Equity		$ 0