Leases (Tables)

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Schedule of Rent Expense

Total rental expense for the years ended December 31, 2017, 2016 and 2015 was as follows (in thousands):

	2017		2016		2015
Rental expense:
Marine equipment — barges	$	11,550	$	13,791	$	14,092
Marine equipment — towing vessels		116,690		137,609		143,067
Other buildings and equipment		15,915		11,182		9,383
Rental expense	$	144,155	$	162,582	$	166,542

Schedule of Future Minimum Lease Payments under Operating Leases

Future minimum lease payments under operating leases that have initial or remaining noncancelable lease terms in excess of one year at December 31, 2017 were as follows (in thousands):

	Land, Buildings		Marine Equipment
	And Equipment		Barges		Towing Vessels		Total
2018	$	18,888	$	8,711	$	59,185	$	86,784
2019		15,153		4,573		8,727		28,453
2020		12,432		3,806		2,578		18,816
2021		11,384		1,567		2,578		15,529
2022		9,436		1,567		2,578		13,581
Thereafter		73,382		896		12,889		87,167
	$	140,675	$	21,120	$	88,535	$	250,330