Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income (Loss)	$ 31,054	$ (37,060)	$ 35,929		$ 18,803
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			35,908		29,906
Provision for doubtful accounts			399		1,925
Provision for warranty and returns			513		2,031
Stock compensation			11,759		8,805
Loss on disposal of property and equipment			360		3,010
Bond premium amortization			204		0
Debt Issuance Costs amortization			144		0
Bargain purchase gain			0		(63,237)
Change in fair value of contingent earn-out	6,000	6,000	2,000		6,000
Asset Impairment Charges			269		0
Impairment of Intangible Assets, Finite-lived			5,000		0
Other Noncash Expense			2,167		1,804
Cash provided by (used in) changes in operating assets and liabilities
Accounts receivable			(43,260)		(70,606)
Inventories			12,124		66,870
Prepaid expenses and other assets			3,494		(95,254)
Related-party receivables			24,143		0
Accounts payable			17,459		8,785
Accrued liabilities			(36,387)		66,479
Income taxes, including excess tax benefits and deferred income taxes			(13,268)		(14,185)
Net cash provided by operating activities			58,957		(28,864)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment			(47,365)		(27,199)
Proceeds from sale of asset			13,000		2
Business acquisitions, net of cash acquired			1,300		157,097
Intangible assets additions			(4,047)		(2,005)
Purchases of investment securities			(8,480)		0
Proceeds from sale of investment securities			8,900		0
Net cash used in investing activities			(39,292)		(186,299)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options			12,536		10,944
Proceeds from employee stock purchase plan			0		1,326
Purchase of treasury stock			(5,469)		(3,739)
Net cash (used in) provided by financing activities			7,067		8,531
Effect of exchange rate changes on cash			(7,707)		2,473
NET DECREASE IN CASH AND CASH EQUIVALENTS			19,025		(204,159)
CASH AND CASH EQUIVALENTS, beginning of period			290,072	[1]	445,082	$ 445,082
CASH AND CASH EQUIVALENTS, end of period	309,097	240,923	309,097		240,923	290,072	[1]
NON-CASH INVESTING ACTIVITIES
Capital Expenditures Incurred but Not yet Paid			2,508		6,024
Fair Value of Assets Acquired			0		881,732
Payments to Acquire Businesses, Net of Cash Acquired			0		(157,097)
Proceeds from Issuance of Debt			0		(75,000)	(75,000)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred			0		7,512
Business Combination, Contingent Consideration, Liability, Noncurrent	0	(19,000)	0		(19,000)	(19,000)
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable			0		(413,139)	$ (450,400)
BARGAIN PURCHASE GAIN	$ 0	$ 0	0		(63,237)
Goodwill, Period Increase (Decrease)			0		1,015
Increase (Decrease) in Assumed Liabilities			0		162,786
Tangent [Member]
NON-CASH INVESTING ACTIVITIES
BARGAIN PURCHASE GAIN			$ 0		$ (63,237)

[1] December 31, 2017 balances were derived from audited consolidated financial statements.