Quarterly report pursuant to Section 13 or 15(d)

Basis of presentation (Details)

v3.8.0.1
Basis of presentation (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2018
USD ($)
segment
Mar. 31, 2017
USD ($)
Interim Consolidated Financial Information    
Number of operating segments | segment 2  
Other Nonoperating Income (Expense) $ (203) $ (236)
Income Tax Expense (Benefit) $ (1,262) (2,694)
Accounting Standards Updates 2017-07 [Member]    
Interim Consolidated Financial Information    
Other Nonoperating Income (Expense)   179
Accounting Standards Update 2016-09    
Interim Consolidated Financial Information    
Income Tax Expense (Benefit)   $ 616