Nature of Operations and Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
Mar. 31, 2015 item	Mar. 31, 2014	Sep. 30, 2014
Nature of Operations and Basis of Presentation
Number of building materials segments	2hw_NumberOfBuildingMaterialsSegments
Percentage of total revenue and cost of revenue for services	10.00%	13.00%
Reclassification of debt issue costs to offset related debt liabilities	$ 10.6		$ 7.1

Reclassification of debt issue costs to offset related debt liabilities.

No definition available.

Name:	hw_ReclassificationOfDebtIssueCostsToOffsetDebtCarryingValue
Namespace Prefix:	hw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration