Note 2 - Summary of Accounting Policies (Details Textual) $ in Thousands		12 Months Ended
	Oct. 31, 2018	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Depreciation, Total		$ 25,296	$ 23,127	$ 21,465
Goodwill and Intangible Asset Impairment, Total		0	0	0
Number of Reporting Units	0
Amortization of Financing Costs and Debt Discount Premium		4,749	3,516	3,939
Deferred Costs Amortization Expense, Next Twelve Months		4,828
Deferred Costs Amortization Expense, Year Two		4,985
Deferred Costs Amortization Expense, Year Three		5,120
Deferred Costs Amortization Expense, Year Four		5,272
Deferred Costs Amortization Expense, Year Five		2,236
Contract with Customer, Liability, Total		14,174	4,594
Contract with Customer, Liability, Revenue Recognized		4,592
Advertising Expense		34,792	45,926	45,488
Research and Development Expense, Total		50,019	$ 42,869	$ 37,163
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member] | Minimum [Member]
Finance and Operating Lease, Right-of-Use Asset					$ 65,000
Finance and operating Lease, Liability					65,000
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member] | Maximum [Member]
Finance and Operating Lease, Right-of-Use Asset					75,000
Finance and operating Lease, Liability					$ 75,000
Fair Value, Inputs, Level 2 [Member]
Debt Instrument, Fair Value Disclosure, Total		849,809
Term Loan [Member]
Long-term Debt, Total		$ 857,851
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Number of Major Customers		1	1
Concentration Risk, Percentage		11.00%	7.00%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Number of Major Customers		0	0	0
Concentration Risk, Percentage		6.00%	6.00%	7.00%