Employee Retirement and Postretirement Benefits - Additional Information (Detail)	9 Months Ended
Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]
Minimum requisite service period, years	1 year

Defined Benefit And Defined Contribution Plans, Requisite Service Period

No definition available.

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Namespace Prefix:	df_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration