Note 4 - Financing Arrangements - Outstanding Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Less current portion of long-term debt	$ (249,436)
Long-term debt	755,575	1,085,649
Line of Credit [Member]
Long-term Debt, Total	169,600	241,400
Senior Notes [Member]
Long-term Debt, Total	$ 835,400	$ 844,200

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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