Stock Award Plan (Details) $ in Millions	1 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) shares	Oct. 31, 2013 USD ($) shares	Apr. 30, 2016 USD ($) Director	May 02, 2015 USD ($)	Jul. 31, 2015 USD ($)
Class of Stock [Line Items]
Term of the award plan			5 years
Excess tax benefits accumulated in capital in excess of par value			$ 0.0		$ 0.1
Maximum [Member]
Class of Stock [Line Items]
Compensation expense			0.1	$ 0.1
Unrecognized compensation expense			$ 0.1
Class A [Member]
Class of Stock [Line Items]
Shares awarded (in shares) | shares		16,387
Shares awarded, value		$ 0.2
Share-based award, vesting period			3 years
Class A [Member] | Directors Chairman [Member]
Class of Stock [Line Items]
Shares awarded (in shares) | shares	4,533
Number of directors | Director			3
Class A [Member] | Directors Chairman [Member] | Maximum [Member]
Class of Stock [Line Items]
Shares awarded, value	$ 0.1