Summary of significant accounting policies and basis of presentation (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	$ 29,331
Operating lease liability	$ 34,814
ASU 2016-02 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset		$ 31,000
Operating lease liability		$ 36,700