CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 24,341	$ 28,640
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	95,705	85,209
Amortization of operating lease right-of-use assets	47,542	51,573
Equity in earnings of joint ventures, net of dividends	5,012	(8,350)
Amortization of deferred financing costs and loan discount	2,240	1,943
(Gain) on contribution of imaging centers into joint venture	(16,808)	0
(Gain) loss on sale and disposal of equipment and other	1,183	962
Amortization of cash flow hedge, net of taxes	2,765	2,771
Non-cash change in fair value of interest rate hedge	949	(39,576)
Stock-based compensation	21,380	19,112
Loss on impairment	3,949	0
Change in fair value of contingent consideration	(4,112)	(329)
Changes in operating assets and liabilities, net of assets acquired and liabilities assumed in purchase transactions:
Accounts receivable	(1,379)	(36,686)
Other current assets	5,754	(4,934)
Other assets	(16,641)	3,738
Deferred taxes	7,389	8,955
Operating lease liability	(43,390)	(49,597)
Deferred revenue	1,155	(7,809)
Accounts payable, accrued expenses and other	(5,091)	37,148
Net cash provided by (used in) operating activities	131,943	92,770
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of imaging centers and other acquisitions	(10,915)	(26,009)
Purchase of property and equipment	(136,537)	(98,606)
Proceeds from sale of equipment	82	3,008
Equity contributions in existing and purchase of interest in joint ventures	(5,453)	(1,441)
Net cash provided by (used in) investing activities	(152,823)	(123,048)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on notes payable	(1,929)	0
Payments on term loan debt	(11,062)	(9,938)
Proceeds from sale of economic interest in majority owned subsidiary, net of taxes	5,102	0
Distributions paid to noncontrolling interests	(3,523)	0
Payments on contingent consideration	(3,390)	0
Proceeds from issuance of common stock, net of issuance costs	245,831	0
Proceeds from issuance of common stock upon exercise of options	72	0
Net cash provided by (used in) financing activities	231,101	(9,938)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	(171)	616
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	210,050	(39,600)
CASH AND CASH EQUIVALENTS, beginning of period	127,834	134,606
CASH AND CASH EQUIVALENTS, end of period	337,884	95,006
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	59,421	30,251
Cash paid during the period for income taxes	$ 225	$ 560