Joint Venture - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jan. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Gain on contribution to joint venture					$ 12,964,000
Accumulated deficit	$ (476,932,000)			$ (476,932,000)		$ (481,713,000)
Goodwill	57,909,000			57,909,000		57,717,000	$ 57,770,000
Impairment of goodwill		$ 0
Accuray Asia
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture								49.00%
Gain on contribution to joint venture			$ 13,000,000.0
Non cash revenue recognized from joint venture				1,400,000
Joint venture associated costs				200,000
Deferred of intra-entity profit margin	1,700,000			1,700,000		$ 1,800,000
Previously deferred intra-entity margin from system sales	400,000			1,900,000
Deferral of intra entity margin from system sales	800,000			1,700,000
Accumulated deficit	900,000			900,000
Equity method investment	16,600,000			16,600,000
Proportional share of underlying equity in net assets	13,800,000			13,800,000
Equity method investment, intra-entity profit				1,700,000
Goodwill	$ 4,500,000			4,500,000
Impairment of goodwill				$ 0