CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Total Radnet, Inc.'s Equity	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2017			47,723,915
Beginning balance, value at Dec. 31, 2017	$ 69,925	$ 61,560	$ 5	$ 212,261	$ (548)	$ (150,158)	$ 8,365
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)			5,000
Issuance of common stock upon exercise of options	10	10		10
Issuance of common stock under the equity compensation plan (in shares)			607,160
Issuance of common stock under the equity compensation plan	0
Stock-based compensation expense	6,364	6,364		6,364
Forfeiture of restricted stock (in shares)			(1,150)
Forfeiture of restricted stock	(7)	(7)		(7)
Sale of noncontrolling interests, net of taxes	40,779	15,593		15,593			25,186
Special distribution from noncontrolling interest	(6,281)	2,894		2,894			(9,175)
Distributions paid to noncontrolling interests	(913)						(913)
Purchase of noncontrolling interests	(200)	(43)		(43)			(157)
Change in cumulative foreign currency translation adjustment	(65)	(65)			(65)
Change in fair value cash flow hedge, net of taxes	4,889	4,889			4,889
Net income (loss)	6,786	3,107				3,107	3,679
Ending balance (in shares) at Sep. 30, 2018			48,334,925
Ending balance, value at Sep. 30, 2018	121,287	94,302	$ 5	237,072	4,276	(147,051)	26,985
Beginning balance (in shares) at Jun. 30, 2018			48,284,925
Beginning balance, value at Jun. 30, 2018	124,934	87,305	$ 5	235,713	3,677	(152,090)	37,629
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)			5,000
Issuance of common stock upon exercise of options	10	10		10
Issuance of common stock under the equity compensation plan (in shares)			45,000
Issuance of common stock under the equity compensation plan	0
Stock-based compensation expense	1,568	1,568		1,568
Special distribution from noncontrolling interest	(6,281)	2,894		2,894			(9,175)
Distributions paid to noncontrolling interests	(5,116)	(3,070)		(3,070)			(2,046)
Purchase of noncontrolling interests	(200)	(43)		(43)			(157)
Change in cumulative foreign currency translation adjustment	4	4			4
Change in fair value cash flow hedge, net of taxes	595	595			595
Net income (loss)	5,773	5,039				5,039	734
Ending balance (in shares) at Sep. 30, 2018			48,334,925
Ending balance, value at Sep. 30, 2018	121,287	94,302	$ 5	237,072	4,276	(147,051)	26,985
Beginning balance (in shares) at Dec. 31, 2018			48,977,485
Beginning balance, value at Dec. 31, 2018	200,253	127,184	$ 5	242,835	2,259	(117,915)	73,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)			10,000
Issuance of common stock upon exercise of options	50	50		50
Issuance of common stock under the equity compensation plan (in shares)			726,042
Issuance of common stock under the equity compensation plan	0
Stock-based compensation expense	6,993	6,993		6,993
Issuance of common stock for purchase of membership interest (in shares)			440,207
Issuance of common stock for purchase of membership interest in HVRA	6,000	6,000		6,000
Forfeiture of restricted stock (in shares)			(1,500)
Forfeiture of restricted stock	(5)	(5)		(5)
Sale of noncontrolling interests, net of taxes	5,098	3,090		3,090			2,008
Distributions paid to noncontrolling interests	(1,818)						(1,818)
Contribution from noncontrolling partner	750						750
Issuance of common stock for purchase (in shares)			(101,902)
Issuance of common stock for purchase	1,500	1,500		1,500
Change in cumulative foreign currency translation adjustment	(28)	(28)			(28)
Change in fair value of cash flow hedge, net of taxes	(14,481)	(14,481)			(14,481)
Net income (loss)	10,760	4,360				4,360	6,400
Ending balance (in shares) at Sep. 30, 2019			50,254,136
Ending balance, value at Sep. 30, 2019	215,072	134,663	$ 5	260,463	(12,250)	(113,555)	80,409
Beginning balance (in shares) at Jun. 30, 2019			50,127,234
Beginning balance, value at Jun. 30, 2019	212,430	133,918	$ 5	257,607	(6,942)	(116,752)	78,512
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the equity compensation plan (in shares)			25,000
Issuance of common stock under the equity compensation plan	0
Stock-based compensation expense	1,356	1,356		1,356
Issuance of common stock for purchase (in shares)			101,902
Issuance of common stock for purchase	1,500	1,500		1,500
Change in cumulative foreign currency translation adjustment	(23)	(23)			(23)
Change in fair value of cash flow hedge, net of taxes	(5,283)	(5,283)			(5,283)
Other	0				(2)	2
Net income (loss)	5,092	3,195				3,195	1,897
Ending balance (in shares) at Sep. 30, 2019			50,254,136
Ending balance, value at Sep. 30, 2019	$ 215,072	$ 134,663	$ 5	$ 260,463	$ (12,250)	$ (113,555)	$ 80,409