Segment Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2020 USD ($) segment region state	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) state region	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of states in which home building segments operate \| state	13		13
Number of regions in which entity operates \| region	3		3
Number of homebuilding segments \| segment	3
Segment Reporting Information [Line Items]
Revenue	$ 533,112	$ 482,738	$ 1,440,329	$ 1,306,038
Operating income	23,151	9,543	43,521	(125,901)
Depreciation and amortization	3,780	3,242	10,834	8,912
Capital expenditures			7,510	16,365
Assets	2,002,163		2,002,163		$ 1,957,644
Inventory Write-down			1,100	131,700
Write off capitalized interest and capitalized indirect cost			1,200	16,900
Operating Segments
Segment Reporting Information [Line Items]
Operating income	66,784	48,558	159,142	(13,171)
Depreciation and amortization	3,257	2,849	9,261	7,816
Corporate and unallocated
Segment Reporting Information [Line Items]
Operating income	(43,633)	(39,015)	(115,621)	(112,730)
Depreciation and amortization	523	393	1,573	1,096
Capital expenditures			353	3,507
Assets	624,013		624,013		560,763
West Segment
Segment Reporting Information [Line Items]
Revenue	303,500	238,723	825,629	658,097
West Segment \| Operating Segments
Segment Reporting Information [Line Items]
Operating income	42,574	29,268	106,128	(53,489)
Depreciation and amortization	2,119	1,415	5,778	3,956
Capital expenditures			3,606	8,172
Assets	720,268		720,268		751,110
East Segment
Segment Reporting Information [Line Items]
Revenue	108,126	118,356	297,107	301,168
East Segment \| Operating Segments
Segment Reporting Information [Line Items]
Operating income	12,423	11,247	29,257	23,571
Depreciation and amortization	500	658	1,605	1,743
Capital expenditures			1,699	2,122
Assets	317,228		317,228		286,340
Southeast Segment
Segment Reporting Information [Line Items]
Revenue	121,486	125,659	317,593	346,773
Southeast Segment \| Operating Segments
Segment Reporting Information [Line Items]
Operating income	11,787	8,043	23,757	16,747
Depreciation and amortization	638	$ 776	1,878	2,117
Capital expenditures			1,852	$ 2,564
Assets	$ 340,654		$ 340,654		$ 359,431

Inventory Impairment, Results of Discounted Cash Flow Analysis

No definition available.

Name:	bzh_InventoryImpairmentResultsofDiscountedCashFlowAnalysis
Namespace Prefix:	bzh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of Regions in which Entity Operates

+ References

No definition available.

+ Details

Name:	bzh_NumberofRegionsinwhichEntityOperates
Namespace Prefix:	bzh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Write Off Capitalized Interest and Capitalized Indirect Cost

+ References

No definition available.

+ Details

Name:	bzh_WriteOffCapitalizedInterestAndCapitalizedIndirectCost
Namespace Prefix:	bzh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 3: 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)(12))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

+ Details

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

- Definition

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

+ Details

Name:	us-gaap_DepreciationAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_OperatingIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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

- 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_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- 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:	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: