XML 151 R135.htm IDEA: XBRL DOCUMENT v3.8.0.1
Commitments and contingencies (Minimum payments under lease agreements) (Details) - Property Rental Agreements [Member]
$ in Thousands
Dec. 31, 2017
USD ($)
Operating Leased Assets [Line Items]  
2018 $ 10,211
2019 7,692
2020 7,593
2021 7,670
2022 7,750
Thereafter 44,388
Head lease payments $ 85,304