Credit Arrangements - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Credit arrangements
Total long-term debt	$ 254,645	$ 261,570
Less: current portion	(62,697)	(58,189)
Long-term debt, net of current portion	191,948	203,381
Commercial equipment notes
Credit arrangements
Total long-term debt	153,987	161,148
Mortgages
Credit arrangements
Total long-term debt	11,372	7,564
Senior Notes
Credit arrangements
Total long-term debt	$ 89,286	$ 92,858

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+ References

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-Publisher FASB
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