Inventory - Total Owned Inventory by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Segment Reporting Information [Line Items]
Projects in progress	$ 1,534,306	$ 1,463,055
Land held for future development	28,531	28,531
Land held for sale	11,443	12,662
Total owned inventory	1,574,280	1,504,248
Corporate and unallocated
Segment Reporting Information [Line Items]
Projects in progress	196,228	192,287
Land held for future development	0	0
Land held for sale	0	0
Total owned inventory	196,228	192,287
West Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	733,525	723,094
Land held for future development	3,483	3,483
Land held for sale	4,235	5,160
Total owned inventory	741,243	731,737
East Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	270,930	228,937
Land held for future development	14,077	14,077
Land held for sale	3,810	4,104
Total owned inventory	288,817	247,118
Southeast Segment \| Operating Segments
Segment Reporting Information [Line Items]
Projects in progress	333,623	318,737
Land held for future development	10,971	10,971
Land held for sale	3,398	3,398
Total owned inventory	$ 347,992	$ 333,106

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: