Per Common Share Amounts (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2017 shares	Mar. 31, 2016 shares	Mar. 31, 2017 shares	Mar. 31, 2016 shares	Sep. 30, 2016 shares
Class of Stock [Line Items]
Weighted average common stock shares outstanding basic (in shares)	16,025,000	16,002,000	16,025,000	16,001,000
Weighted average common stock shares outstanding diluted (in shares)	16,042,000	16,002,000	16,036,000	16,001,000
Class A membership units
Class of Stock [Line Items]
Conversion ratio			1
Weighted average common stock shares outstanding diluted (in shares)			30,094,557
Class A common shares
Class of Stock [Line Items]
Common stock shares authorized	31,600,000		31,600,000		31,600,000
Class A common shares | Class A membership units
Class of Stock [Line Items]
Membership shares (in units)	15,094,557		15,094,557
Class B-1 common shares
Class of Stock [Line Items]
Weighted average common stock shares outstanding basic (in shares)			1,000,000
Common stock shares authorized	1,000,000		1,000,000		1,000,000
Conversion ratio			1
Capital Unit Redeemable Class A Units
Class of Stock [Line Items]
Common stock shares authorized	15,000,000		15,000,000