Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income	$ 130,241	$ 89,388	$ 101,931
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	9,200	8,170	4,860
Amortization of debt issuance costs and accretion of original issue discount	122	122	122
Share-based Compensation	4,609	3,434	1,820
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	3,795	1,885	1,820
Increase (Decrease) in Deferred Compensation	0	19	115
Loss on disposal of fixed assets	49	89	55
Deferred income taxes	11,988	(12,071)	14,835
Tax Benefit from exercise of stock options, operating activities	0	(1,536)	0
Provision for class action legal settlement	0	32,000	0
Payment for class action legal settlement	(32,000)	0	0
Increase (Decrease) in Operating Capital [Abstract]
Increase (Decrease) in Accounts Receivable	(35,509)	(1,487)	(26,245)
Increase (Decrease) in Inventories	12,493	5,140	(20,746)
Increase (Decrease) in Prepaid Expense and Other Assets	(2,109)	(1,189)	(1,917)
Increase (Decrease) in Accounts Payable	4,563	(1,733)	9,910
Increase (Decrease) in Other Operating Liabilities	23,596	17,873	5,395
Net Cash Provided by (Used in) Operating Activities	127,243	138,219	90,135
Net Cash Provided by (Used in) Investing Activities [Abstract]
Capital expenditures	(56,345)	(9,556)	(32,948)
Increase (Decrease) in Restricted Cash	(308)	0	(350)
Proceeds from the sale of fixed assets	15	0	0
Net Cash Provided by (Used in) Investing Activities	(56,638)	(9,556)	(33,298)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of Long-term Debt	(3,960)	(3,960)	(3,960)
Tax Benefit from exercise of stock options, financing activities	0	1,536	0
Proceeds from Stock Options Exercised	1,915	2,251	37
Net Cash Provided by (Used in) Financing Activities	(2,045)	(173)	(3,923)
Effect of Exchange Rate on Cash and Cash Equivalents	(157)	(25)	0
Cash and Cash Equivalents, Period Increase (Decrease)	68,403	128,465	52,914
Cash and Cash Equivalents	$ 292,656	$ 224,253	$ 95,788