Consolidated Balance Sheets (Parenthetical) - USD ($)	Jan. 02, 2018	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Accounts receivable, allowances		$ 16,003,000	$ 13,095,000	$ 23,058,000
Convertible preferred stock, par value		$ 0.01	$ 0.01	$ 0.01
Convertible preferred stock. aggregate liquidation preference		$ 400,000,000	$ 400,000,000	$ 400,000,000
Convertible preferred stock, shares authorized		400,000	400,000	400,000
Convertible preferred stock, shares issued		400,000	400,000	400,000
Convertible preferred stock, shares outstanding		400,000	400,000	400,000
Common stock (voting), par value		$ 0.01	$ 0.01	$ 0.01
Common stock (voting), shares authorized		100,000,000	100,000,000	100,000,000
Common Stock (voting), issued		68,836,258	68,574,176	68,475,871
Common Stock (voting), outstanding		68,836,258	68,574,176	68,475,871
Undesignated Preferred Stock, shares authorized		5,000,000	5,000,000	5,000,000
Undesignated Preferred Stock, issued		0	0	0
Undesignated Preferred Stock, outstanding		0	0	0
Allied Acquisition [Member] | Investment Agreement [Member] | Series A Cumulative Convertible Participating Preferred Stock [Member]
Convertible preferred stock, par value	$ 0.01
Convertible preferred stock. aggregate liquidation preference	$ 400,000,000.0
Convertible preferred stock, shares issued	400,000
Convertible preferred stock. liquidation preference per share	$ 1,000
Preferred stock conversion price per share	$ 41.26
Preferred stock dividend rate	6.00%
Common stock to be issued upon conversion of convertible preferred stock	9,694,619