Consolidated Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net income	$ 11,893	$ 19,820
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	8,164	7,459
Deferred income tax benefit	(5,173)	(2,483)
Stock compensation	1,818	1,358
Defined benefit plan expense (income)	45	(9)
Provision of doubtful accounts	574	125
Gain on revaluation of financial derivatives	(456)	(324)
(Gain) loss on sale of property and equipment	29	(8)
Changes in operating assets and liabilities:
Accounts receivable	(21,906)	(15,994)
Inventory	(1,223)	(5,762)
Prepaid expenses and other assets	(1,628)	(3,905)
Accounts payable	6,392	15,522
Accrued liabilities	7,819	(6,970)
Net cash provided by operating activities	6,348	8,829
Investing Activities:
Investment in subsidiary, net of cash acquired		(47)
Proceeds from the sale of property and equipment	18	181
Purchases of property and equipment	(17,010)	(10,403)
Net cash used in investing activities	(16,992)	(10,269)
Financing Activities:
Borrowing of debt	75,000
Repayments of debt	(446)	(1,669)
Excess tax benefit from equity awards	(385)
Cash paid for financing costs	(650)
Cash paid for the cancellation of restricted stock	(793)	(467)
Proceeds from the exercise of Common Stock options	204	2,026
Net cash provided by (used in) financing activities	72,930	(110)
Foreign currency effect	3,791	(4,569)
Net increase (decrease) in cash and cash equivalents	66,077	(6,119)
Cash and cash equivalents at beginning of period	144,479	85,700
Cash and cash equivalents at end of period	210,556	79,581
Supplemental disclosure of cash flow information:
Cash paid for taxes	9,342	14,768
Cash paid for interest	458	515
Supplemental disclosure of non-cash transactions:
Common Stock issued to Board of Directors and employees	$ 984	$ 673