Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income	$ 87,224	$ 54,989	$ 40,054
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and software	33,293	33,254	27,724
Amortization of intangible assets	9,691	24,342	22,555
Amortization of deferred financing costs	564	564	2,258
Gain on sale of cost basis investment	(7,697)	0	0
Stock-based compensation expense	21,901	21,507	24,143
Deferred income taxes	7,290	(3,504)	(20,409)
Noncash lease expense	4,133	0	0
Change in fair value of contingent consideration	0	(35)	(2,865)
Release of estimated liability for appeals, net	(10,478)	(8,436)	0
Release of estimated liability for appeals, net
Accounts receivable	(16,292)	(17,312)	(6,976)
Prepaid expenses and other current assets	(10,487)	(2,785)	(1,298)
Other assets	(2,173)	245	124
Income taxes receivable / (payable)	15,607	(16,925)	1,462
Accounts payable, accrued expenses and other liabilities	4,744	11,181	(340)
Operating lease liabilities	(5,315)	0	0
Liability for appeals	1,227	(628)	32
Net cash provided by operating activities	133,232	96,457	86,464
Investing activities:
Acquisition of businesses, net of cash acquired	(185,790)	0	(171,321)
Proceeds from sale of cost basis investment	9,776	0	0
Investment in common stock	(7,421)	0	0
Purchases of property and equipment	(8,276)	(11,264)	(17,318)
Investment in capitalized software	(13,348)	(19,149)	(15,725)
Net cash used in investing activities	(205,059)	(30,413)	(204,364)
Financing activities:
Proceeds from credit facility	0	0	42,204
Payments for deferred financing costs	0	0	(2,269)
Proceeds from exercise of stock options	39,332	38,362	2,720
Payments of tax withholdings on behalf of employees for net-share settlements	(6,988)	(2,818)	(3,161)
Payments on capital lease obligations	(195)	0	(143)
Purchases of treasury stock	0	(5,955)	(14,137)
Net cash provided by financing activities	32,149	29,589	25,214
Net (decrease)/increase in cash and cash equivalents	(39,678)	95,633	(92,686)
Cash and Cash Equivalents
Cash and cash equivalents at beginning of year	178,946	83,313	175,999
Cash and cash equivalents at end of period	139,268	178,946	83,313
Supplemental disclosure of cash flow information:
Cash (refunds received)/paid for income taxes, net of refunds	(5,298)	22,225	17,995
Cash paid for interest	10,457	10,326	9,944
Supplemental disclosure of non-cash activities:
Change in balance of accrued property and equipment purchases	$ (1,303)	$ 1,305	$ 51