Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 10,564	$ 3,050
Adjustments to reconcile net income to net cash provided from (used in) operating activities:
Depreciation, depletion, and amortization	9,207	10,090
Amortization of deferred financing costs in interest expense	261	230
Stock-based compensation expense (non-cash)	771	2,338
Deferred income tax (benefit) expense	(359)	(696)
Changes in assets and liabilities net of acquired assets and liabilities:
Decrease (increase) in accounts receivable	(8,582)	(13,644)
Decrease (increase) in inventory	5,097	(9,593)
Decrease (increase) in prepaid and other current assets	(634)	(1,435)
Increase (decrease) in accounts payable and accrued expenses	(16,308)	(835)
Increase (decrease) in interest and taxes payable	1,626	(1,237)
Domestic pension plan contributions	(9,000)	(4,000)
Other-net	(818)	(1,097)
Net cash used in operating activities	(8,175)	(16,829)
Cash flows from investing activities:
Payments for purchase of property, plant, and equipment	(7,867)	(6,128)
Payments for mine development	(1,661)	(200)
Payments for acquisition	0	(16,406)
Proceeds from sale of property, plant, and equipment	3	16
Net cash used in investing activities	(9,525)	(22,718)
Cash flows from financing activities:
Proceeds from issuance of short-term debt	0	6,186
Proceeds from issuance of long-term debt	0	27,000
Repayment of long-term debt	(190)	(5,180)
Principal payments under capital lease obligations	(211)	(190)
Cash dividends paid	(2,012)	(1,895)
Deferred financing costs	0	(300)
Repurchase of common stock	0	(405)
Payments of withholding taxes for stock-based compensation awards	(2,133)	(1,480)
Net cash (used in) provided by financing activities	(4,546)	23,736
Effects of exchange rate changes	608	688
Net change in cash and cash equivalents	(21,638)	(15,123)
Cash and cash equivalents at beginning of period	41,844	31,464
Cash and cash equivalents at end of period	$ 20,206	$ 16,341