Joint Venture - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jan. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Accumulated deficit	$ 488,024,000		$ 488,024,000		$ 488,024,000
Investee's currency translation adjustment			46,000		243,000
Goodwill	58,006,000		$ 58,006,000		57,960,000	$ 57,717,000
Impairment of goodwill	$ 0
Accuray Asia
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture	49.00%		49.00%				49.00%
Deferred of intra-entity profit margin	$ 3,100,000		$ 3,100,000		$ 2,100,000
Previously deferred intra-entity margin from system sales	1,000,000.0	$ 600,000	1,200,000	$ 1,500,000
Deferral of intra entity margin from system sales	200,000	$ 300,000	2,200,000	$ 900,000
Accumulated deficit	500,000		500,000
Equity method investment	14,700,000		14,700,000
Proportional share of underlying equity in net assets	13,100,000		13,100,000
Investee's currency translation adjustment			900,000
Elimination of equity method investment intra-entity profit on sales			3,100,000
Proportional share of underlying equity in net assets, difference amount	1,600,000		1,600,000
Goodwill	$ 4,700,000		4,700,000
Impairment of goodwill			$ 0