Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019
Common Stock Class A Non-voting
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01000
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)	52,097,590	52,565,064	52,475,070
Common stock, shares outstanding (in shares)	52,097,590	52,565,064	52,475,070
Common Stock Class B Voting
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01000
Common stock, shares authorized (in shares)	3,000,000	3,000,000	3,000,000
Common stock, shares issued (in shares)	2,970,171	2,970,171	2,970,171.000
Common stock, shares outstanding (in shares)	2,970,171	2,970,171	2,970,171