Summary of Significant Accounting Policies - Pension and Postretirement Benefits (Details) $ in Thousands	Jan. 01, 2007 USD ($)
Postretirement Health Care Benefits
Pension and Postretirement Benefits
Maximum liability related to total retiree health care costs under plan amendment	$ 5,000

Represents the amount of liability related to total retiree health care costs capped under postretirement benefit plan amendment.

No definition available.

Name:	hayn_PostretirementBenefitPlansAmountOfLiabilityCapped
Namespace Prefix:	hayn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration