Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended			12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 219	$ 136	$ 36,148		$ 18,939
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			55,069		47,512
Provision for doubtful accounts			638		1,906
Provision for warranty and returns			1,817		3,639
Stock compensation			17,992		13,387
Loss on disposal of property and equipment			760		3,177
Bond premium amortization			313		12
Debt Issuance Costs amortization			216		0
Bargain purchase gain			0		(71,771)
Change in fair value of contingent earn-out	18,500	7,000	20,500		13,000
Asset Impairment Charges			269		0
Impairment of Intangible Assets, Finite-lived			5,000		0
Other Noncash Expense			2,100		1,690
Cash provided by (used in) changes in operating assets and liabilities
Accounts receivable			(38,957)		(51,498)
Inventories			12,201		148,482
Prepaid expenses and other assets			(1,826)		6,214
Related-party receivables			31,004		(131,617)
Accounts payable			(2,094)		17,551
Accrued liabilities			(18,509)		63,234
Income taxes, including excess tax benefits and deferred income taxes			(12,359)		(13,982)
Net cash provided by operating activities			110,282		69,875
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment			(75,057)		(51,702)
Proceeds from sale of asset			13,000		2
Business acquisitions, net of cash acquired			(1,300)		(157,097)
Intangible assets additions			(5,375)		(3,718)
Purchases of investment securities			(30,495)		(24,743)
Proceeds from sale of investment securities			14,940		0
Net cash used in investing activities			(84,287)		(237,258)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options			14,211		19,967
Proceeds from employee stock purchase plan			0		2,705
Payments Related to Tax Withholding for Share-based Compensation			6,119		3,951
Net cash (used in) provided by financing activities			8,092		18,721
Effect of exchange rate changes on cash			(5,343)		4,194
NET INCREASE DECREASE IN CASH AND CASH EQUIVALENTS			28,744		(144,468)
CASH AND CASH EQUIVALENTS, beginning of period			290,072	[1]	445,082	$ 445,082
CASH AND CASH EQUIVALENTS, end of period	318,816	300,614	318,816		300,614	290,072	[1]
NON-CASH INVESTING ACTIVITIES
Capital Expenditures Incurred but Not yet Paid			1,184		1,435
Fair Value of Assets Acquired					893,582
Payments to Acquire Businesses, Net of Cash Acquired					(157,097)
Proceeds from Issuance of Debt					(75,000)	(75,000)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred					7,512
Business Combination, Contingent Consideration, Liability, Noncurrent		(19,000)			(19,000)	(19,000)
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable					(413,139)	$ (450,400)
BARGAIN PURCHASE GAIN	$ 0	$ (8,534)	0		(71,771)
Goodwill, Period Increase (Decrease)					1,015
Increase (Decrease) in Assumed Liabilities					166,102
Tangent [Member]
NON-CASH INVESTING ACTIVITIES
BARGAIN PURCHASE GAIN					$ (71,771)

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