Balance Sheet Components - Performance Awards Liability (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2020 USD ($) day board_member tranche $ / shares	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Number of Board Members, performance awards | board_member	2
Accrued bonuses		$ 2,200		$ 2,100
Unrecognized bonus compensation expense		2,300
Bonus compensation expense		$ 100	$ 0
Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Performance bonuses approved	$ 8,100
Performance bonus, number of tranches | tranche	2
Percent of bonus subject to performance condition	50.00%
Stock price threshold to earn bonus, tranche one (USD per share) | $ / shares	$ 31.61
Performance bonus, stock price, threshold consecutive trading days | day	20
Performance bonus, percent of amount, tranche two	50.00%
Stock price threshold to earn bonus, tranche two (USD per share) | $ / shares	$ 32.99
Senior Executive
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Performance bonuses approved	$ 100
Two Board Of Director Members
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Performance bonuses approved	$ 300
Performance bonus, number of tranches | tranche	2
Stock price threshold to earn bonus, tranche one (USD per share) | $ / shares	$ 31.61
Stock price threshold to earn bonus, tranche two (USD per share) | $ / shares	$ 32.99
Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Unrecognized bonus compensation expense, period		3 months 3 days
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Unrecognized bonus compensation expense, period		11 months 4 days
Accrued Liabilities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Accrued bonuses		$ 2,200		1,500
Other Long-Term Liabilities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Accrued bonuses		$ 0		$ 600