Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows from Operating Activities
Net income	$ 16,454	$ 15,047
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,826	5,554
Distributions received from equity method investee	0	7,131
Deferred income taxes	729	577
Share-based compensation	1,968	1,737
Equity method investment loss	0	348
Changes in operating assets and liabilities:
Receivables, net	(1,411)	(8,845)
Inventory	(13,338)	(6,693)
Prepaid expenses	(620)	(1,148)
Accounts payable	(5,106)	(671)
Accounts payable to affiliate, net	0	(168)
Accrued expenses	(3,232)	(934)
Income taxes payable/refundable	446	(426)
Deferred credit	(362)	(410)
Accrued retirement health and life insurance benefits	(111)	(256)
Net cash provided by operating activities	1,243	10,843
Cash Flows from Investing Activities
Additions to plant, property and equipment	(13,065)	(9,933)
Return of equity method investment	0	299
Net cash used in investing activities	(13,065)	(9,634)
Cash Flows from Financing Activities
Purchase of treasury stock for tax withholding on share-based compensation	(2,073)	(1,131)
Payment of dividends and dividend equivalents	(2,750)	(1,376)
Principal payments on long-term debt	(185)	(177)
Proceeds from credit agreement	16,946	12,467
Payments on credit agreement	(920)	(4,650)
Net cash provided by financing activities	11,018	5,133
Increase (decrease) in cash and cash equivalents	(804)	6,342
Cash and cash equivalents, beginning of period	3,084	1,569
Cash and cash equivalents, end of period	$ 2,280	$ 7,911