Note 8 - Segment Reporting - Adjusted EBITDA (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total adjusted EBITDA		$ 102,230	$ 69,726	$ 174,011	$ 116,429
Interest expense		(11,002)	(10,893)	(21,115)	(21,681)
Depreciation and amortization		(11,600)	(12,986)	(23,283)	(25,583)
Non-cash write-down and other adjustments (1)	[1]	(1,316)	(1,710)	(2,622)	(1,876)
Non-cash share-based compensation expense (2)	[2]	(3,885)	(3,186)	(6,991)	(5,818)
Gain (Loss) on Extinguishment of Debt, Total	[3]	(1,332)		(1,332)
Transaction costs and credit facility fees (4)	[4]	(441)	(420)	(703)	(736)
Business optimization expenses (5)	[5]	(29)	(1,346)	(167)	(1,446)
Other		(12)	69	1	(30)
Income before provision for income taxes		72,613	39,254	117,799	59,259
Domestic [Member]
Total adjusted EBITDA		90,602	63,692	156,077	105,583
International [Member]
Total adjusted EBITDA		$ 11,628	$ 6,034	$ 17,934	$ 10,846

[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.