Note 15 - Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Asset Retirement Obligations [Table Text Block]

	Year Ended December 31,
	2016		2015
	(Dollars in thousands)
Balance at beginning of year	$	20,856	$	19,142
Revision in estimated cash flows		303		(681	)
Liabilities incurred		540		859
Accretion expense		1,649		1,536
Balance at end of year	$	23,348	$	20,856