Note 13 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Beginning Balance, Shares (in shares)	5,554,000
Beginning Balance, Weighted Average Exercise Price (in dollars per share)	$ 17.35
Granted, Shares (in shares)	1,010,000
Granted, Weighted Average Exercise Price (in dollars per share)	$ 19.58
Exercised, Shares (in shares)	(2,017,442)	(172,326)	(510,512)
Exercised, Weighted Average Exercise Price (in dollars per share)	$ 19.14
Forfeitures, Shares (in shares)	(114,000)
Forfeitures, Weighted Average Exercise Price (in dollars per share)	$ 17.74
Expired, Shares (in shares)	(31,000)
Expired, Weighted Average Exercise Price (in dollars per share)	$ 22.34
Ending Balance, Shares (in shares)	4,402,000	5,554,000
Ending Balance, Weighted Average Exercise Price (in dollars per share)	$ 17.07	$ 17.35
Ending Balance, Weighted Average Remaining Contractual Terms (Year)	5 years 292 days
Outstanding, Aggregate intrinsic value	$ 48,339
Expected to Vest, Shares (in shares)	1,481,000
Expected to Vest, Weighted Average Exercise Price (in dollars per share)	$ 18.60
Expected to Vest, Weighted Average Remaining Contractual Terms (Year)	8 years 80 days
Expected to Vest, Aggregate Intrinsic Value	$ 14,119
Exercisable, Shares (in shares)	2,370,000
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 15.87
Exercisable, Weighted Average Remaining Contractual Terms (Year)	3 years 302 days
Exercisable, Aggregate Intrinsic Value	$ 29,068