Consolidated Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities:
Net income	$ 66,979	$ 50,290
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	23,123	24,565
Deferred income tax benefit	(4,262)	(6,294)
Stock compensation	4,687	3,449
Defined benefit plan expense (income)	284	(33)
Provision of doubtful accounts	309	500
Gain on revaluation of financial derivatives	(951)	(1,264)
Gain from equity investment		(785)
Loss on write-off of intangible assets	358
(Gain) loss on sale of property and equipment	(41)	202
Changes in operating assets and liabilities:
Accounts receivable	(24,442)	(25,190)
Inventory	(3,829)	(4,000)
Prepaid expenses and other assets	(1,313)	(8,240)
Accounts payable	1,722	8,039
Accrued liabilities	3,712	4,212
Net cash provided by operating activities	66,336	45,451
Investing Activities:
Acquisition and investment in subsidiary, net of cash acquired	(47)	(31,739)
Proceeds from the sale of property and equipment	226	96
Purchases of property and equipment	(35,728)	(26,990)
Net cash used in investing activities	(35,549)	(58,633)
Financing Activities:
Borrowing of debt	15,000	91,592
Repayments of debt	(4,156)	(76,904)
Excess tax benefit from equity awards	1,220	4,004
Cash paid for the cancellation of restricted stock	(1,475)
Proceeds from the exercise of Common Stock options	6,468	6,282
Net cash provided by financing activities	17,057	24,974
Foreign currency effect	(4,372)	(1,508)
Net increase in cash and cash equivalents	43,472	10,284
Cash and cash equivalents at beginning of period	85,700	54,885
Cash and cash equivalents at end of period	129,172	65,169
Supplemental disclosure of cash flow information:
Cash paid for taxes	23,870	13,181
Cash paid for interest	1,420	1,990
Supplemental disclosure of non-cash transactions:
Common Stock issued to Board of Directors and employees	$ 2,287	$ 2,026