CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 33,608	$ 44,319	$ (1,749)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	115,877	96,694	86,795
Amortization of operating lease right-of-use assets	68,847	73,967	67,915
Lease abandonment charges	0	19,675	0
Equity in earnings of joint ventures, net of dividends	(5,952)	(6,260)	1,577
Amortization and write off of deferred financing costs and loan discount	2,693	3,254	4,413
Loss on sale and disposal of equipment and other	2,529	1,246	1,200
Loss (gain) on extinguishment of debt	0	1,496	(4,047)
Loss on impairment	0	0	4,170
Amortization of cash flow hedge	3,687	3,695	3,448
Non-cash change in fair value of interest rate swap	(39,621)	(21,670)	2,528
Stock-based compensation	23,770	25,203	12,405
Non cash item in other expenses	0	0	242
Change in value of contingent consideration	(325)	0	0
Changes in operating assets and liabilities, net of assets acquired and liabilities assumed in purchase transactions:
Accounts receivable	(30,078)	(5,890)	25,206
Other current assets	(3,327)	(15,777)	6,588
Other assets	(12,166)	662	(5,425)
Deferred taxes	13,356	19,834	(611)
Operating lease liability	(68,943)	(72,553)	(53,906)
Deferred revenue	(7,316)	(28,319)	37,941
Accounts payable, accrued expenses and other liabilities	49,778	9,915	45,069
Net cash provided by operating activities	146,417	149,491	233,759
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of imaging centers and other operations	(129,961)	(77,691)	(31,265)
Purchase of property and equipment	(119,451)	(137,874)	(94,172)
Purchase of intangible assets	0	(5,130)	0
Proceeds from sale of equipment	3,904	625	828
Equity contributions in existing and purchase of interest in joint ventures	(1,441)	(1,441)	(1,635)
Net cash used in investing activities	(246,949)	(221,511)	(126,244)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments on term loan debt	(53,750)	(619,529)	(43,296)
Principal payments on notes and leases payable other than term loan debt	0	(3,302)	(3,562)
Additional deferred finance costs on revolving loan amendment	0	(938)	(741)
Proceeds from debt issuance, net of issuance costs	147,996	717,307	0
Proceeds from paycheck protection program loans	0	0	4,023
Distributions paid to noncontrolling interests	(893)	(2,426)	(1,985)
Proceeds from sale of economic interest in majority owned subsidiary	0	13,073	0
Proceeds from revolving credit facility	0	128,300	250,900
Payments on revolving credit facility	0	(128,300)	(250,900)
Proceeds from issuance of common stock upon exercise of options	294	488	0
Net cash provided by (used in) financing activities	93,647	104,673	(45,561)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	113	(65)	(101)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(6,772)	32,588	61,853
CASH AND CASH EQUIVALENTS, beginning of period	134,606	102,018	40,165
CASH AND CASH EQUIVALENTS, end of period	127,834	134,606	102,018
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	39,151	29,042	39,521
Cash paid during the period for income taxes	$ 587	$ 1,950	$ 5,069