Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of future rental payments under operating leases

Future rental payments under operating leases in respect of equipment rentals and leased premises are payable as follows:

Year ended December 31,	$’000
2018	12,072
2019	10,879
2020	10,919
2021	11,422
2022	9,283
2023 and thereafter	141,832
	196,407