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

Commitments and contingencies (Minimum payments under lease agreements) (Details)

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