Retirement Plans - Schedule of Accumulated Other Comprehensive Income (Loss) Expected to be Recognized as Components of Net Periodic Benefit Cost (Detail) - Defined Benefit Plans $ in Millions	12 Months Ended
Sep. 30, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Prior service credit	$ 0.2
Net loss	(4.4)
Total	$ (4.2)

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

No definition available.

Name:	us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration