Stockholders' Deficit - Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Sep. 23, 2017	Feb. 24, 2015	Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Class of Stock [Line Items]
Shares authorized			110,000,000.0
Common stock, shares authorized			100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.0001		$ 0.0001	$ 0.0001
Preferred stock, shares authorized			10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.0001		$ 0.0001	$ 0.0001
Cash dividends			$ (4.3)
Common Stock
Class of Stock [Line Items]
Common stock, shares authorized			100,000,000.0
Common stock, par value (in dollars per share)			$ 0.0001
Common shares sold in private placement (in shares)		2,500,000
Shares issued in private placement, price per share (in dollars per share)		$ 10.00
Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized			10,000,000
Preferred stock, par value (in dollars per share)			$ 0.0001
Issuance of stock (in shares)		500,000
Shares repurchased during period			100,000
Liquidation preference per share (in dollars per share)			$ 100.00
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized		2,000,000.0	2,000,000
Shares of common stock issued upon conversion			8.6
Conversion price (in dollars per share)			$ 11.59
Dividend rate (as a percent)	7.625%		7.625%
Undesignated Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized			8,000,000
School Bus Holdings, Inc.
Class of Stock [Line Items]
Shares issued for acquisition (in shares)		12,000,000
Hennessy Capital | Common Stock | Backstop Commitment Investor
Class of Stock [Line Items]
Shares acquired (in shares)		102,750
Common Stock
Class of Stock [Line Items]
Issuance of stock (in shares)					2,500,000
Shares repurchased during period			864,752		10,000,000
Series A Preferred Stock dividend - Common Stock (in shares)			0	95,934	182,088