Income taxes (Details) - USD ($) shares in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Uncertain tax positions	$ 0
LLC Units
Income Tax Contingency [Line Items]
Redemption of LLC Units (in shares)	1,400	261
Tax Receivable Agreement
Income Tax Contingency [Line Items]
Percentage due to related parties	85.00%
Pre-IPO LLC Members \| Tax Receivable Agreement
Income Tax Contingency [Line Items]
Percentage due to related parties	85.00%
Due to related parties	$ 13,400,000	$ 1,700,000
Due to related parties, current	$ 9,000	$ 9,000

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