Revenue - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Sep. 30, 2025
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Customer support arrangement term			1 year
Revenue expected to be recognized from remaining performance obligations		$ 853,543	$ 853,543
Revenue recognized in period, included in opening deferred revenue balance		$ 119,244	$ 264,029
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage		61.00%	61.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period		12 months	12 months
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Customer support arrangement term			1 year
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Customer support arrangement term			3 years
Software-as-a-service \| Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Subscription arrangement term			1 year
Software-as-a-service \| Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Subscription arrangement term			3 years
Subscription
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized from remaining performance obligations		$ 95,302	$ 95,302
Subscription \| Forecast
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage recognized	16.00%
Subscription \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage		49.00%	49.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period		12 months	12 months
Customer support
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized from remaining performance obligations		$ 52,955	$ 52,955
Customer support \| Forecast
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage recognized	9.00%
Customer support \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage		36.00%	36.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period		12 months	12 months
Other services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized from remaining performance obligations		$ 29,564	$ 29,564
Other services \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage		100.00%	100.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period		12 months	12 months

COMMVAULT SYSTEMS INC 10-Q