Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Future Minimum Lease Payments

The future minimum lease payments relating to operating leases are summarized as follows (in thousands of dollars):

2017	50,274
2018	41,967
2019	31,468
2020	18,666
2021	11,375
2022 and after	14,442
	168,192