Note 18 - Subsequent Event (Details Textual) - The 2019 Revolving Credit Facility [Member] - PNC Bank, National Associations [Member] - Subsequent Event [Member] $ in Thousands	Mar. 29, 2019 USD ($)
Line of Credit Facility, Maximum Borrowing Capacity	$ 750,000
Line of Credit Facility, Maximum Amount Of Additional Borrowings	500,000
Line of Credit Facility, Minimum Borrowing Amount Required for Additional Borrowings	25,000
Proceeds from Long-term Lines of Credit	$ 575,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	0.875%