CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES:
Net income	$ 20,388	$ 46,316
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	62,281	54,353
Non-cash impairment charges	3,290	0
Deferred income tax	(935)	(2,919)
Amortization of debt issuance costs	1,178	1,623
Non-cash interest expense	0	6,300
Realized loss on sale of short-term investment	2,287	0
Loss on disposal of property and equipment	443	1,046
Change in fair value of contingent consideration and other	(2,773)	81
Share-based compensation	16,359	12,773
Changes in assets and liabilities, net of business acquisitions:
Accounts receivable	(9,861)	(8,100)
Inventories	(862)	(9,061)
Prepaid expenses and other current assets	(14,691)	1,051
Other non-current assets	(1,977)	(552)
Accounts payable, accrued expenses and other current liabilities	24,021	5,831
Deferred revenue	1,405	1,381
Other non-current liabilities	2,442	(247)
Net cash provided by operating activities	102,995	109,876
INVESTING ACTIVITIES:
Purchases of property and equipment	(29,806)	(26,136)
Proceeds from sale of short-term investments	16,951	0
Proceeds from note receivable	483	0
Proceeds from sale of property and equipment	157	266
Cash used in business acquisition, net of cash acquired	(225,552)	0
Cash received from business acquisition purchase price adjustment	0	225
Change in restricted cash	0	4,165
Net cash used in investing activities	(237,767)	(21,480)
FINANCING ACTIVITIES:
Borrowings under senior credit facility	571,383	15,000
Repayments under senior credit facility	(65,000)	(48,750)
Net cash paid for contingent consideration	(4,661)	0
Principal payments under capital lease obligations	0	(487)
Proceeds from exercised stock options	9,774	9,925
Cash taxes paid in net equity settlement	(6,763)	(4,567)
Net cash provided by (used in) financing activities	504,733	(28,879)
Effect of exchange rate changes on cash and cash equivalents	9,927	(51)
Net increase in cash and cash equivalents	379,888	59,466
Cash and cash equivalents at beginning of period	102,055	48,132
Cash and cash equivalents at end of period	$ 481,943	$ 107,598