Income Taxes - Reconciliation of Income Tax (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed tax at federal statutory rate (35%)	$ (10.5)	$ (58.6)	$ (149.4)
Non-deductible goodwill impairment loss	0.0	16.5	70.9
Non-deductible compensation	2.6	0.4	0.8
Non-deductible transaction costs	0.0	0.6	2.8
Domestic production activities deduction	(4.3)	(5.9)	0.0
State income taxes, net of effect on federal tax	(6.2)	(7.2)	(6.6)
Non-taxable interest income	(2.6)	(2.7)	(2.9)
Valuation allowances	3.8	6.7	2.3
Change in deferred tax rates	(2.0)	4.9	(0.9)
Uncertain tax positions	(2.0)	(3.4)	(0.2)
Sale and liquidation of Michael Foods Canadian egg business	(3.6)	0.0	0.0
Enacted tax law and changes	0.7	(0.4)	0.0
Income tax credits	(1.5)	(0.4)	(0.1)
Rate differential on foreign income	(1.8)	(1.4)	(0.1)
Other, net (none in excess of 5% of statutory tax)	0.6	(1.1)	(0.3)
Income tax benefit	$ (26.8)	$ (52.0)	$ (83.7)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
None in excess of 5% of computed tax	5.00%	5.00%	5.00%