Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES
Net income	$ 17,083	$ 12,146
Adjustments to reconcile net income to net cash provided by operations:
Depreciation	3,057	3,587
Amortization	12,029	11,098
Deferred income taxes	655	918
Non-cash stock compensation and retirement savings plan contributions	11,560	10,595
Adjustment to fair value of contingent consideration for purchase of business	1,757	(828)
Amortization of debt issuance costs and discounts	300	122
Write-off of unamortized credit facility fees	0	246
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	11,453	1,415
Other assets	1,157	2,634
Accounts payable	(12,394)	(6,423)
Other liabilities	(3,865)	(5,386)
Net cash provided by operating activities	42,792	30,124
INVESTING ACTIVITIES
Purchase of property and equipment	(3,182)	(2,521)
Capitalization of internally developed software costs	(477)	(762)
Purchase of businesses	(21,213)	(37,886)
Net cash used in investing activities	(24,872)	(41,169)
FINANCING ACTIVITIES
Proceeds from issuance of convertible notes	143,750	0
Payment for convertible notes issuance costs	(4,323)	0
Purchase of convertible notes hedges	(20,686)	0
Proceeds from issuance of convertible notes warrants	12,060	0
Proceeds from line of credit	161,000	223,500
Payments on line of credit	(216,000)	(190,500)
Payment for credit facility financing fees	0	(355)
Payment of contingent consideration for purchase of business	0	(3,258)
Proceeds from the sale of stock through the Employee Stock Purchase Plan	124	135
Purchases of treasury stock	(51,809)	(23,953)
Remittance of taxes withheld as part of a net share settlement of restricted stock vesting	(2,908)	(2,542)
Net cash provided by financing activities	21,208	3,027
Effect of exchange rate on cash and cash equivalents	(488)	353
Change in cash and cash equivalents	38,640	(7,665)
Cash and cash equivalents at beginning of period	6,307	10,113
Cash and cash equivalents at end of period	44,947	2,448
Supplemental disclosures:
Cash paid for income taxes	2,439	3,725
Cash paid for interest	1,277	922
Non-cash investing activity:
Stock issued for purchase of businesses	3,789	9,429
Stock surrendered by sellers in conjunction with net working capital settlement	$ 303	$ 572