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Leases

12 Months Ended

Dec. 31, 2017

Leases. Lease expense was $40.8 million, $41.3 million and $42.9 million in 2017, 2016 and 2015, respectively. The future minimum lease payments relating to operating leases are summarized as follows (in thousands of dollars):



2018	52,112
2019	39,996
2020	27,184
2021	18,147
2022	11,851
2023 and after	17,843

	167,133