Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities
Net income	$ 37,096	$ 47,966
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	51,761	46,529
Amortization of contract acquisition costs	499	754
Amortization of debt issuance costs	582	534
Imputed interest expense and fair value adjustments to contingent consideration	4,320	(786)
Provision for doubtful accounts	542	964
Gain on disposal of assets	(65)	(118)
Impairment losses	5,602	3,066
Loss on assets held-for-sale	5,300
Deferred income taxes	5,368	4,380
Excess tax benefit from equity-based awards	(539)	(420)
Equity-based compensation expense	7,278	8,569
(Gain) loss on foreign currency derivatives	4,649	4,820
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	23,780	4,722
Prepaids and other assets	(12,652)	(6,839)
Accounts payable and accrued expenses	(13,039)	11,857
Deferred revenue and other liabilities	(4,696)	(11,406)
Net cash provided by operating activities	107,146	116,164
Cash flows from investing activities
Proceeds from sale of long-live assets	93	116
Purchases of property, plant and equipment	(38,863)	(49,184)
Investments in non-marketable equity investments		(9,000)
Acquisitions, net of cash acquired of zero and zero, respectively	(400)	(1,776)
Net cash used in investing activities	(39,170)	(59,844)
Cash flows from financing activities
Proceeds from line of credit	1,584,800	1,697,500
Payments on line of credit	(1,555,800)	(1,682,500)
Payments on other debt	(2,306)	(2,556)
Payments of contingent consideration and hold back payments to acquisitions	(9,467)	(11,883)
Dividends paid to shareholders	(8,922)	(8,710)
Payments to noncontrolling interest	(3,237)	(3,557)
Purchase of mandatorily redeemable noncontrolling interest	(4,105)
Proceeds from exercise of stock options	371	459
Excess tax benefit from equity-based awards	539	420
Payments of debt issuance costs	(1,888)	(35)
Purchase of treasury stock	(57,279)	(16,602)
Net cash used in financing activities	(57,294)	(27,464)
Effect of exchange rate changes on cash and cash equivalents	(9,678)	(20,002)
Increase (decrease) in cash and cash equivalents	1,004	8,854
Cash and cash equivalents, beginning of period	60,304	77,316
Cash and cash equivalents, end of period	61,308	86,170
Supplemental disclosures
Cash paid for interest	4,976	4,640
Cash paid for income taxes	16,755	10,924
Non-cash investing and financing activities
Acquisition of long lived assets through capital leases	2,417	5,316
Acquisition of equipment through increase in accounts payable, net	(542)	5,448
Contract acquisition costs credited to accounts receivable	200	820
Dividends declared but not paid	$ 9,342	$ 8,713