Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net income	$ 17,956	$ 17,733
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation, amortization and accretion	7,089	11,271
Amortization of debt related costs	639	696
Provision for bad debt	166	0
Provision for excess and obsolete inventory	1,959	730
Stock-based compensation	4,012	2,107
Loss on extinguishment of debt and debt retirement costs	0	2,161
Deferred taxes	4,539	0
Long-term income tax receivable	(1,528)	(980)
Long-term income tax payable and other long-term liabilities	1,517	1,357
Other	346	404
Increases (decreases) in cash from operating assets and liabilities:
Accounts receivable	(4,223)	(6,368)
Inventory	(6,714)	(4,232)
Other current assets	(581)	(249)
Accounts payable	(2,900)	767
Accrued expenses and other liabilities	(2,667)	694
Net cash provided by operating activities	19,610	26,091
Investing activities
Capital expenditures	(7,761)	(8,301)
Proceeds from sales of assets	1,000	1,234
Net cash used in investing activities	(6,761)	(7,067)
Financing activities
Proceeds from issuance of long-term debt	0	274,313
Payments on long-term debt	(1,431)	(285,265)
Deferred financing costs	0	(1,576)
Payments for public offering costs	0	(74)
Proceeds from stock option exercises	1,140	1,078
Proceeds from issuance of common stock	206	0
Payments for minimum statutory tax withholding related to net share settlement of equity awards	(2,432)	(1,557)
Net cash used in financing activities	(2,517)	(13,081)
Effect of foreign exchange rates on cash and cash equivalents	(158)	33
Net increase in cash and cash equivalents	10,174	5,976
Cash and cash equivalents, beginning of period	76,290	51,178
Cash and cash equivalents, end of period	$ 86,464	$ 57,154