Note 8 - Segment Reporting - Adjusted EBITDA (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Total adjusted EBITDA		$ 124,474	$ 88,442	$ 298,485	$ 204,871
Interest expense		(9,824)	(10,672)	(30,939)	(32,353)
Depreciation and amortization		(11,841)	(13,108)	(35,124)	(38,691)
Non-cash write-down and other adjustments (1)	[1]	(900)	(756)	(3,522)	(2,632)
Non-cash share-based compensation expense (2)	[2]	(2,919)	(2,584)	(9,910)	(8,402)
Gain (Loss) on Extinguishment of Debt, Total	[3]			(1,332)
Transaction costs and credit facility fees (4)	[4]	(1,767)	(234)	(2,470)	(970)
Business optimization expenses (5)	[5]	(583)	(487)	(750)	(1,933)
Other		(46)	(421)	(45)	(451)
Income before provision for income taxes		96,594	60,180	214,393	119,439
Domestic [Member]
Total adjusted EBITDA		117,108	82,817	273,185	188,400
International [Member]
Total adjusted EBITDA		$ 7,366	$ 5,625	$ 25,300	$ 16,471

[1] Includes gains/losses on disposal of assets, unrealized mark-to-market adjustments on commodity contracts, foreign currency gains/losses and certain purchase accounting related adjustments.

[2] Represents share-based compensation expense to account for stock options, restricted stock and other stock awards over their respective vesting periods.

[3] Represents the non-cash write-off of original issue discount and deferred financing costs due to a voluntary prepayment of Term Loan debt.

[4] Represents transaction costs incurred directly in connection with any investment, as defined in our credit agreement; equity issuance, debt issuance or refinancing; together with certain fees relating to our senior secured credit facilities.

[5] Represents charges relating to business optimization and restructuring costs.