Note 2 - Summary of Significant Accounting Policies - Effect of Accounting Policy Adoption (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Operating revenues	$ 449,758	$ 370,350	$ 875,466	$ 734,026
Total operating expenses	429,740	367,661	840,594	729,409
Operating income	20,018	2,689	34,872	4,617
Income (loss) before income tax benefit	(156)	(10,658)	1,819	(18,999)
Income tax provision	(1,191)	(2,261)	(598)	(6,195)
Net income (loss)	1,035	(8,397)	2,417	(12,804)
Net income (loss) attributable to common stockholders	$ 615	$ (8,452)	$ 1,774	$ (12,884)
Basic earnings (loss) per share (in dollars per share)	$ 0.04	$ (1.32)	$ 0.17	$ (2.02)
Basic weighted average of outstanding shares of common stock (in shares)	14,214	6,385	10,321	6,385
Diluted earnings (loss) per share (in dollars per share)	$ 0.04	$ (1.32)	$ 0.17	$ (2.02)
Diluted weighted average of outstanding shares of common stock (in shares)	14,456	6,385	10,443	6,385
Customer receivables, net of allowance of $69 at June 30, 2018	$ 206,558		$ 206,558			$ 186,407
Other current assets	15,892		15,892			12,170
Total current assets	277,924		277,924			248,720
Total assets	842,225		842,225			820,571
Accounts payable	74,944		74,944			80,555
Other accrued liabilities	5,420		5,420			13,901
Deferred income taxes	14,787		14,787			15,630
Accumulated deficit	(40,460)		(40,460)			(43,459)
Stockholder’s equity (deficit)	210,630		210,630			(43,394)
Total stockholder's equity (deficit)	213,562		213,562			(41,105)
Total liabilities, redeemable restricted units and stockholder's equity (deficit)	842,225		842,225			$ 820,571
Receivables			17,531	$ 7,246
Other assets			3,777	1,361
Accounts payable and other accrued liabilities			(15,353)	(12,934)
Deferred income tax benefit			(959)	$ (7,077)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Operating revenues	449,772		875,315
Total operating expenses	430,759		842,135
Operating income	19,013		33,180
Income (loss) before income tax benefit	(1,161)		127
Income tax provision	(1,482)		(1,089)
Net income (loss)	321		1,216
Net income (loss) attributable to common stockholders	$ (99)		$ 573
Basic earnings (loss) per share (in dollars per share)	$ (0.01)		$ 0.06
Basic weighted average of outstanding shares of common stock (in shares)	14,214		10,321
Diluted earnings (loss) per share (in dollars per share)	$ (0.01)		$ 0.05
Diluted weighted average of outstanding shares of common stock (in shares)	14,456		10,443
Customer receivables, net of allowance of $69 at June 30, 2018	$ 202,555		$ 202,555
Other current assets	13,676		13,676
Total current assets	271,705		271,705
Total assets	836,006		836,006
Accounts payable	72,344		72,344
Other accrued liabilities	5,071		5,071
Deferred income taxes	14,178		14,178
Accumulated deficit	(43,121)		(43,121)
Stockholder’s equity (deficit)	207,969		207,969
Total stockholder's equity (deficit)	210,901		210,901
Total liabilities, redeemable restricted units and stockholder's equity (deficit)	836,006		836,006
Receivables			17,682
Other assets			5,528
Accounts payable and other accrued liabilities			(15,143)
Deferred income tax benefit			(468)
Accounting Standards Update 2014-09 [Member]
Accumulated deficit					$ 1,500
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Operating revenues	14		(151)
Total operating expenses	1,019		1,541
Operating income	(1,005)		(1,692)
Income (loss) before income tax benefit	(1,005)		(1,692)
Income tax provision	(291)		(491)
Net income (loss)	(714)		(1,201)
Net income (loss) attributable to common stockholders	$ (714)		$ (1,201)
Basic earnings (loss) per share (in dollars per share)	$ (0.05)		$ (0.12)
Basic weighted average of outstanding shares of common stock (in shares)	14,214		10,321
Diluted earnings (loss) per share (in dollars per share)	$ (0.05)		$ (0.12)
Diluted weighted average of outstanding shares of common stock (in shares)	14,456		10,443
Customer receivables, net of allowance of $69 at June 30, 2018	$ (4,003)		$ (4,003)
Other current assets	(2,216)		(2,216)
Total current assets	(6,219)		(6,219)
Total assets	(6,219)		(6,219)
Accounts payable	(2,600)		(2,600)
Other accrued liabilities	(349)		(349)
Deferred income taxes	(609)		(609)
Accumulated deficit	(2,661)		(2,661)
Stockholder’s equity (deficit)	(2,661)		(2,661)
Total stockholder's equity (deficit)	(2,661)		(2,661)
Total liabilities, redeemable restricted units and stockholder's equity (deficit)	$ (6,219)		(6,219)
Receivables			151
Other assets			1,751
Accounts payable and other accrued liabilities			210
Deferred income tax benefit			$ 491