Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net Income (Loss)	$ (60,408)	$ 66,335	$ 130,964
Income from discontinued operations	0	(3,767)	(22,950)
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation and amortization	36,171	35,636	32,147
Amortization of premiums, discounts and issuance costs	1,239	1,765	4,335
Goodwill impairment	168,312	0	0
Loss on early extinguishment of debt	0	57,016	14,532
Stock-based compensation expense	12,323	16,127	18,968
Deferred income taxes	3,239	(22,771)	(31,239)
Gain on sale of building	0	0	(7,280)
Other	(3,167)	144	(2,350)
Changes in assets and liabilities:
Accounts receivable	26,276	(5,543)	(72,731)
Prepaid expenses and other current assets	514	15,928	41,530
Other long-term assets	22,851	17,196	9,799
Accounts payable and accrued expenses	(11,921)	420	21,326
Income taxes (payable) receivable	(21,677)	18,225	(2,285)
Long-term professional liabilities	837	5,600	1,523
Other liabilities	(28,508)	(19,999)	(22,529)
Net cash provided by operating activities - continuing operations	146,081	182,312	113,760
Net cash used in operating activities - discontinued operations	(8,756)	(15,371)	(37,023)
Net cash provided by operating activities	137,325	166,941	76,737
Cash flows from investing activities:
Acquisition payments, net of cash acquired	(6,667)	(28,167)	(29,930)
Purchases of investments	(31,893)	(17,346)	(15,052)
Proceeds from maturities or sales of investments	22,905	16,889	16,496
Purchases of property and equipment	(33,328)	(29,708)	(32,249)
Proceeds from Sale of Buildings	0	0	24,728
Strategic investments	0	0	(20,000)
Other	807	1,378	584
Net cash used in investing activities - continuing operations	(48,176)	(56,954)	(55,423)
Net cash provided by investing activities - discontinued operations	0	0	2,350
Net cash used in investing activities	(48,176)	(56,954)	(53,073)
Cash flows from financing activities:
Borrowings on credit agreement	470,000	830,000	0
Payments on credit agreement	(474,000)	(826,000)	0
Redemption of senior notes, including call premium	0	(1,046,880)	(759,848)
Proceeds from issuance of senior notes and term loan	0	650,000	0
Payments on term loan	(12,500)	(9,375)	0
Payments for credit facility amendment and financing costs	0	(8,621)	0
Payments of contingent consideration liabilities	(1,817)	0	(189)
Payments on finance lease obligations	(2,618)	(2,916)	(2,809)
Proceeds from Issuance of Common Stock	4,912	5,396	6,853
Repurchases of common stock	(919)	(88,511)	(4,719)
Other	(8,773)	9,353	596
Net cash used in financing activities - continuing operations	(25,715)	(487,554)	(760,116)
Net cash used in financing activities - discontinued operations	0	0	0
Net Cash Provided by (Used in) Financing Activities, Total	(25,715)	(487,554)	(760,116)
Net increase (decrease) in cash and cash equivalents	63,434	(377,567)	(736,452)
Cash, cash equivalents at beginning of year	9,824	387,391	1,123,843
Cash and cash equivalents at end of year	73,258	9,824	387,391
Supplemental disclosure of cash flow information:
Interest	42,278	116,235	86,537
Income taxes	30,835	26,908	54,728
Non-cash investing and financing activities:
Equipment financed through finance leases	132	282	6,762
Property and equipment included in accounts payable	$ 2,874	$ 2,589	$ 2,300