Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Income taxes (Summary of valuation allowance) (Details)

v3.19.3.a.u2
Income taxes (Summary of valuation allowance) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Deferred Tax Assets, Valuation Allowance [Roll Forward]    
Valuation allowance at beginning of period $ 92,298 $ 104,858
Decrease of allowance to income tax provision (17,937) (12,560)
Valuation allowance at end of period $ 74,361 $ 92,298