Consolidated Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net income	$ 50,562	$ 66,979
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	27,724	23,123
Deferred income tax benefit	(1,933)	(4,262)
Stock compensation	6,856	4,687
Defined benefit plan expense	151	284
Provision of doubtful accounts	385	309
Gain on revaluation of financial derivatives		(951)
Loss on write-off or intangible assets		358
Loss (gain) on sale of property and equipment	291	(41)
Changes in operating assets and liabilities:
Accounts receivable	(22,835)	(24,442)
Inventory	(5,647)	(3,829)
Prepaid expenses and other assets	2,826	(1,313)
Accounts payable	6,508	1,722
Accrued liabilities	6,123	3,712
Net cash provided by operating activities	71,011	66,336
Investing Activities:
Proceeds from the sale of property and equipment	45	226
Acquisition of subsidiary, net of cash acquired	(73,593)	(47)
Purchases of property and equipment	(50,742)	(35,728)
Net cash used in investing activities	(124,290)	(35,549)
Financing Activities:
Borrowing of debt	75,000	15,000
Repayments of debt	(32,368)	(4,156)
Excess tax (expense) benefit from equity awards	(277)	1,220
Cash paid for financing costs	(650)
Cash paid for the cancellation of restricted stock	(1,196)	(1,475)
Proceeds from the exercise of Common Stock options	1,038	6,468
Net cash provided by financing activities	41,547	17,057
Foreign currency effect	66	(4,372)
Net (decrease) increase in cash and cash equivalents	(11,666)	43,472
Cash and cash equivalents at beginning of period	144,479	85,700
Cash and cash equivalents at end of period	132,813	129,172
Supplemental disclosure of cash flow information:
Cash paid for taxes	18,183	23,870
Cash paid for interest	1,963	1,420
Supplemental disclosure of non-cash transactions:
Common Stock issued to Board of Directors and employees	$ 3,507	$ 2,287