Employee Benefit Plans - Stock Incentive Plan, Stock Options and RSUs (Details) $ in Millions	1 Months Ended					12 Months Ended
	Sep. 30, 2021 shares	Sep. 30, 2015 shares	Oct. 31, 2014 shares	Sep. 30, 2012 shares	Sep. 30, 2009 shares	Mar. 31, 2022 USD ($) plan shares
Employee Benefit Plans
Number of stock incentive plans | plan						2
Options vested and expected to vest, outstanding, aggregate intrinsic value | $						$ 5.9
Stock options
Employee Benefit Plans
Options, exercisable, number (in shares)						3,769,000
2007 Plan
Employee Benefit Plans
Increase in number of shares of common stock authorized and reserved for issuance under the plan		1,000,000	1,500,000	800,000	800,000
Stock options authorized under the plan (in shares)		4,950,000	3,950,000	2,450,000	1,650,000
2007 Plan | Restricted stock units
Employee Benefit Plans
Vesting percentage						25.00%
Vesting period						4 years
Number of shares of common stock receivable upon vesting of each RSU						1
2016 Plan
Employee Benefit Plans
Increase in number of shares of common stock authorized and reserved for issuance under the plan	3,360,000
2016 Plan | Stock options
Employee Benefit Plans
Vesting percentage						25.00%
Vesting period						4 years
Options or other stock-based awards granted (in shares)						3,000,000
2016 Plan | Minimum | Restricted stock units
Employee Benefit Plans
Vesting period						1 year
2016 Plan | Maximum | Stock options
Employee Benefit Plans
Expiration term						10 years
2016 Plan | Maximum | Restricted stock units
Employee Benefit Plans
Vesting period						4 years