Acquisition of Interstate Distributor Co. (Tables)

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

	(in thousands)
Cash and cash equivalents	$	6,316
Trade and other accounts receivable	35,131
Other current assets	2,426
Property and equipment	71,964
Other non-current assets	1,244
Intangible assets	7,800
Goodwill	32,198
Total assets	157,079
Accounts payable, accrued expenses, and current portion of long-term debt	(35,209		)
Insurance accruals	(10,826		)
Long-term debt	(17,404		)
Other accruals	(596		)
Total consideration transferred	$	93,044

Business Acquisition, Pro Forma Information [Text Block]

TOTAL PURCHASE PRICE CONSIDERATION	(in thousands)
Cash paid pursuant to Stock Purchase Agreement	$	93,044
Cash acquired included in historical book value of IDC assets and liabilities	(6,316		)
Net cash paid	$	86,728

	Year ended		Year ended
	December 31, 2016		December 31, 2017
	(in thousands)
Operating revenue	$	938,007	$	756,498
Net income	$	54,222	$	72,752