CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES:
Net income (loss)	$ 34,004	$ (21,067)	$ 41,204
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	61,128	47,010	52,611
Non-cash impairment charges	790	47,078	0
Deferred income tax provision (benefit)	(964)	(13,145)	1,537
Share-based compensation	15,105	10,393	9,051
Amortization of debt issuance costs	2,571	2,298	2,725
Non-cash interest expense	7,104	6,463	8,520
Payment of accreted interest	0	0	(30,617)
Loss on disposal of property and equipment	1,201	1,965	1,312
Excess tax benefits from stock-based compensation arrangements	(1,384)	(270)	(3,634)
Change in fair value of contingent consideration	(764)	0	0
Changes in assets and liabilities, net of business acquisitions:
Accounts receivable	(16,145)	(2,892)	3,783
Inventories	(27,006)	(35,505)	(711)
Prepaid expenses and other current assets	8,070	4,823	(3,067)
Other non-current assets	(1,744)	441	(553)
Accounts payable, accrued expenses and other current liabilities	2,427	9,945	(21,071)
Deferred revenue	1,118	697	(1,051)
Other non-current liabilities	(6,048)	(4,966)	(939)
Net cash provided by operating activities	79,463	53,268	59,100
INVESTING ACTIVITIES:
Cash used in business acquisitions, net of cash acquired	(320,921)	(2,980)	(7,278)
Purchases of property and equipment	(41,921)	(47,851)	(69,031)
Sales of property and equipment	0	535	0
Purchases of short-term investments	0	0	(67,907)
Maturities of short-term investments	0	0	64,940
Other changes in intangible assets	(475)	0	0
Net cash used in investing activities	(363,317)	(50,296)	(79,276)
FINANCING ACTIVITIES:
Borrowings under senior credit facility	425,000	30,000	155,000
Repayments under senior credit facility	(195,000)	(165,000)	(12,812)
Proceeds from the issuance of common stock, net of issuance costs	0	152,458	0
Payment of liability component of convertible notes	0	0	(134,383)
Payment of capital lease obligation	(605)	0	0
Debt issuance costs	(3,210)	(1,053)	(385)
Proceeds from exercised stock options	15,215	2,344	696
Excess tax benefits from stock-based compensation arrangements	1,384	270	3,634
Net cash provided by financing activities	242,784	19,019	11,750
Effect of exchange rate changes on cash and cash equivalents	(7,550)	1,685	4,556
Net increase (decrease) in cash and cash equivalents	(48,620)	23,676	(3,870)
Cash and cash equivalents at beginning of period	120,614	96,938	100,808
Cash and cash equivalents at end of period	$ 71,994	$ 120,614	$ 96,938