Inventory - Total Owned Inventory by Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Projects in progress	$ 1,660,841	$ 1,601,330
Land held for future development	28,531	83,173
Land held for sale	13,352	7,781
Total owned inventory	1,702,724	1,692,284
Corporate and unallocated
Segment Reporting Information [Line Items]
Projects in progress	210,784	198,990
Land held for future development	0	0
Land held for sale	0	24
Total owned inventory	210,784	199,014
West Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	773,121	763,453
Land held for future development	3,483	58,125
Land held for sale	5,750	0
Total owned inventory	782,354	821,578
East Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	297,575	280,761
Land held for future development	14,077	14,077
Land held for sale	4,511	4,580
Total owned inventory	316,163	299,418
Southeast Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	379,361	358,126
Land held for future development	10,971	10,971
Land held for sale	3,091	3,177
Total owned inventory	$ 393,423	$ 372,274

Carrying amount as of the balance sheet date of project in progress

No definition available.

Name:	bzh_InventoryProjectsInProgress
Namespace Prefix:	bzh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of parcels of land held for sale, and on which the entity has no intention or no further intention to perform construction activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryLandHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net carrying amount as of the balance sheet date of the sum of the various components of an operative builder's inventory, including finished homes. Operative builders primarily consist of entities that develop land, construct residential homes and commercial and industrial buildings thereon, and sell them to home buyers and operators of the commercial and industrial properties.

+ References

+ Details

Name:	us-gaap_InventoryOperativeBuilders
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of land available for development.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),1(d))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

+ Details

Name:	us-gaap_LandAvailableForDevelopment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_CorporateNonSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=bzh_WestSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=bzh_EastSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=bzh_SoutheastSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: