Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net income	$ 35,961	$ 24,447
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	30,758	34,950
Amortization of contract acquisition costs	809	334
Amortization of debt issuance costs	341	412
Imputed interest expense and fair value adjustments to contingent consideration	31	195
Provision for doubtful accounts	313	224
(Gain) loss on disposal of assets	12	(41)
Gain on sale of business	(30)
Loss on assets held-for-sale	3,178
Deferred income taxes	5,901	5,897
Excess tax benefit from equity-based awards	(703)	(521)
Equity-based compensation expense	4,836	4,584
(Gain) loss on foreign currency derivatives	575	62
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	26,669	23,945
Prepaids and other assets	(22,656)	(14,544)
Accounts payable and accrued expenses	27,281	(19,423)
Deferred revenue and other liabilities	12,179	(5,476)
Net cash provided by operating activities	125,455	55,045
Cash flows from investing activities
Proceeds from sale of long-live assets	22	63
Purchases of property, plant and equipment	(29,589)	(27,743)
Proceeds from sale of business	250
Investments in non-marketable equity investments	(1,384)
Acquisitions, net of cash acquired of zero and zero, respectively	(79,574)	(400)
Net cash used in investing activities	(110,275)	(28,080)
Cash flows from financing activities
Proceeds from line of credit	1,151,700	1,186,500
Payments on line of credit	(1,112,000)	(1,151,500)
Payments on other debt	(3,025)	(1,214)
Payments of contingent consideration and hold back payments to acquisitions	(435)	(9,467)
Dividends paid to shareholders	(10,069)	(8,923)
Payments to noncontrolling interest	(1,800)	(2,202)
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	(1,876)	(2,019)
Excess tax benefit from equity-based awards		521
Payments of debt issuance costs	(3)	(1,883)
Purchase of treasury stock	(18,328)	(36,111)
Net cash provided by financing activities	6,314	(30,032)
Effect of exchange rate changes on cash and cash equivalents	1,152	(1,907)
Increase (decrease) in cash and cash equivalents	22,646	(4,974)
Cash and cash equivalents, beginning of period	55,264	60,304
Cash and cash equivalents, end of period	77,910	55,330
Supplemental disclosures
Cash paid for interest	4,857	3,155
Cash paid for income taxes	5,905	13,705
Non-cash investing and financing activities
Acquisition of long lived assets through capital leases	874	2,667
Acquisition of equipment through increase in accounts payable, net	$ (1,274)	289
Contract acquisition costs credited to accounts receivable		$ 200