Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net income	$ 51,536	$ 37,096
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,273	51,761
Amortization of contract acquisition costs	1,273	499
Amortization of debt issuance costs	521	582
Imputed interest expense and fair value adjustments to contingent consideration	39	(4,320)
Provision for doubtful accounts	380	542
(Gain) loss on disposal of assets	85	(65)
Gain on sale of business	(3,323)
Impairment losses		5,602
Loss on assets held-for-sale	3,178	5,300
Deferred income taxes	8,155	5,368
Excess tax benefit from equity-based awards	(1,970)	(539)
Equity-based compensation expense	8,358	7,278
(Gain) loss on foreign currency derivatives	829	4,649
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	13,460	23,780
Prepaids and other assets	(26,814)	(12,652)
Accounts payable and accrued expenses	32,597	(9,347)
Deferred revenue and other liabilities	14,066	(4,696)
Net cash provided by operating activities	149,643	110,838
Cash flows from investing activities
Proceeds from sale of long-live assets	31	93
Purchases of property, plant and equipment	(43,932)	(38,863)
Proceeds from sale of business	391
Investments in non-marketable equity investments	(1,384)
Acquisitions, net of cash acquired of zero and zero, respectively	(81,360)	(400)
Net cash used in investing activities	(126,254)	(39,170)
Cash flows from financing activities
Proceeds from line of credit	1,571,837	1,584,800
Payments on line of credit	(1,534,137)	(1,555,800)
Payments on other debt	(4,501)	(2,306)
Payments of contingent consideration and hold back payments to acquisitions	(674)	(9,467)
Dividends paid to shareholders	(10,069)	(8,922)
Payments to noncontrolling interest	(2,745)	(3,237)
Purchase of mandatorily redeemable noncontrolling interest		(4,105)
Proceeds from exercise of stock options	2,150	371
Tax payments related to issuance of restricted stock units	(4,937)	(3,692)
Excess tax benefit from equity-based awards		539
Payments of debt issuance costs	(38)	(1,888)
Purchase of treasury stock	(18,328)	(57,279)
Net cash provided by financing activities	(1,442)	(60,986)
Effect of exchange rate changes on cash and cash equivalents	1,631	(9,678)
Increase (decrease) in cash and cash equivalents	23,578	1,004
Cash and cash equivalents, beginning of period	55,264	60,304
Cash and cash equivalents, end of period	78,842	61,308
Supplemental disclosures
Cash paid for interest	8,138	4,976
Cash paid for income taxes	11,357	16,755
Non-cash investing and financing activities
Acquisition of long lived assets through capital leases	931	2,417
Acquisition of equipment through increase in accounts payable, net	405	(542)
Contract acquisition costs credited to accounts receivable		200
Dividends declared but not paid	$ 11,462	$ 9,342