Employee Benefit Plans - Benefit Payments for Expected Future Service Expected to be Paid (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014
Postretirement Benefits
Pension Plans Postretirement And Other Employee Benefits [Line Items]
2015	$ 82
2016	76
2017	70
2018	64
2019	58
Years 2020-2024	217
Pension Plan
Pension Plans Postretirement And Other Employee Benefits [Line Items]
2015	298
2016	294
2017	286
2018	276
2019	268
Years 2020-2024	$ 1,164

Name:	bzc_PensionPlansPostretirementAndOtherEmployeeBenefitsLineItems
Namespace Prefix:	bzc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant