Quarterly Financial Summary (Unaudited) Quarterly Financial Summary (Unaudited) - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Actuarial gain (loss)	$ (26.7)	$ 30.1
Actuarial gain (loss), net of income tax	$ (18.3)	$ 21.4

Mark-to-market adjustments for the gain or losses occurring on pension or postretirement plans during the year, and any mark-to-market true-up or other adjustments, net of income taxes.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration