Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)		$ (971)	$ (15,345)	$ 44,949
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		65,557	65,647	55,081
Deferred taxes		(11,381)	8,753	(11,091)
Provision for bad debts and sales-related allowances		7,034	12,416	10,678
Provision for inventory obsolescence		6,016	6,312	5,716
Stock-based compensation, net of cash settlements		45,281	26,532	31,726
Change in fair value of contingent obligations		(21,486)	6,980	6,813
Payments of contingent obligations		(699)	(5,906)	0
Non-cash accretion of interest expense on convertible notes and imputed financing obligation		15,239	14,981	13,489
Net change in derivative assets and liabilities		(2,286)	2,938	(2,125)
Other non-cash charges and credits		1,230	2,618	755
Changes in operating assets and liabilities, net of effect of acquired businesses:
Accounts receivable		(7,394)	(29,189)	(31,221)
Inventories		(18,068)	(24,398)	4,510
Other current assets		(18,898)	(9,218)	(6,498)
Accounts payable and other accrued liabilities		27,389	(6,235)	651
Income taxes receivable/payable, net		(3,058)	(5,591)	(2,429)
Net cash provided by operating activities		83,505	51,295	121,004
Cash flows from investing activities:
Purchases of short-term investments		0	(87,623)	(216,349)
Proceeds from sales and maturities of short-term investments		46,624	233,633	252,856
Purchases (Sales) of restricted cash investments		0	5,115	(5,110)
Purchases, net of proceeds from sales, of property and equipment		(12,290)	(13,754)	(22,373)
Proceeds from sale of held-for-sale building and land		1,130	0	0
Businesses and technology purchased, net of cash acquired and dispositions		697	(29,559)	(19,932)
Net cash provided by (used for) investing activities	[1]	36,161	107,812	(10,908)
Cash flows from financing activities:
Proceeds from issuance of convertible senior notes		150,000	0	0
Debt issuance costs		(3,750)	0	0
Proceeds from issuance of common stock		10,522	12,074	11,100
Purchases of treasury stock and net share settlements		(113,509)	(101,844)	(83,292)
Repayment of acquisition-related debt		(11,209)	(9,000)	(8,275)
Contingent consideration payments related to businesses acquired		(2,503)	(25,018)	(28,111)
Repayment of short-term obligations		(755)	(2,094)	(528)
Net cash provided by (used for) financing activities		28,796	(125,882)	(109,106)
Effect of foreign exchange rate changes on cash and cash equivalents		(2,477)	4,196	374
Increase (decrease) in cash and cash equivalents	[1]	145,985	37,421	1,364
Cash, cash equivalents, and restricted cash at beginning of year	[1]	202,876	165,455	164,091
Cash, cash equivalents, and restricted cash at end of year	[1]	$ 348,861	$ 202,876	$ 165,455

[1] Certain prior period amounts have been revised due to the implementation of ASU 2016-18. See Note 1 for details.