Quarterly report pursuant to Section 13 or 15(d)

Income taxes (Details Textual)

v3.10.0.1
Income taxes (Details Textual) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2018
Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent   66.70% 11.00%    
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount $ 2.9        
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent 21.00%        
Effective Income Tax Rate Reconciliation, Deduction, Dividend, Percent         100.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount   $ 1.4     $ 1.9
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent   35.00%      
Scenario, Plan [Member]          
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent       21.00%  
Tax Year 2017 [Member]          
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent         10.50%
Tax Year 2025 [Member]          
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent         13.125%