Note 11 - Goodwill and Intangible Assets - Summary of Changes in Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 30, 2016
Goodwill, gross beginning of year	$ 709,696	$ 583,914
Goodwill, Acquired During Period	3,077	125,782	$ 72,300
Goodwill	(1,752)	0
Goodwill, gross end of year	711,021	709,696	583,914
Accumulated goodwill impairment	(98,596)	(98,596)
Goodwill	$ 612,425	$ 611,100	$ 485,318	$ 485,318