CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 8,576	$ 20,174
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,432	13,915
Loss on disposal of assets	35	415
Deferred income taxes	11,204	3,747
Stock based compensation	1,198	2,762
Accretion of deferred financing fees	130	107
Changes in assets and liabilities:
Accounts and other receivables	(8,746)	42,621
Inventories	13,644	(3,416)
Taxes receivable	(7,654)	397
Accounts payable	(9,752)	(30,674)
Accrued liabilities	2,912	(7,232)
Deferred income and customer advances	(6,626)	(1,862)
Other assets and liabilities	366	1,122
Net cash provided by operating activities	19,719	42,076
Cash flows from investing activities:
Expenditures for property, plant and equipment	(34,100)	(39,512)
Other investing activities	(385)	(587)
Net cash used for investing activities	(34,485)	(40,099)
Cash flows from financing activities:
Borrowings from line of credit	133,500	85,500
Payments of line of credit	(93,500)	(65,500)
Payment of line of credit facility fees	(425)	0
Principal payments of finance leases	(182)	(145)
Purchase of treasury stock	(925)	(23,853)
Issuance of common stock	2	16
Net cash provided by (used for) financing activities	38,470	(3,982)
Net change in cash and cash equivalents	23,704	(2,005)
Cash and cash equivalents at beginning of period	7,050	9,808
Cash and cash equivalents at the end of period	30,754	7,803
Supplemental non-cash investing activities:
Capital expenditures included in accounts payable	11,553	14,039
Supplemental cash activities:
Cash paid for interest	730	1,040
Cash paid for income taxes	$ 109	$ 21