Other Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Accrued Liabilities, Current [Abstract]

Schedule of Accrued Liabilities [Table Text Block]

Other accrued liabilities include the following (in thousands):

	Year Ended December 31,
	2017		2016
Accrued lease expense	$	5,142	$	4,763
Deferred revenue	460		2,245
Other	2,855		3,002
Total	$	8,457	$	10,010