Acquisitions Acquisitions - Racine Purchase Price Allocation (Details) (Racine Federated Inc, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Racine Federated Inc
Assets acquired:
Cash	$ 1,529
Receivables	5,230
Inventories	7,603
Prepaid expenses and other current assets	164
Current deferred income taxes	247
Property, plant and equipment	3,772
Intangible assets	29,100
Goodwill	26,565
Total assets acquired	74,210
Liabilities assumed:
Payables	2,920
Accrued compensation and employee benefits	1,785
Long-term deferred income taxes	11,457
Other long-term liabilities	451
Total liabilities assumed	$ 16,613

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accounts Receivable

No definition available.

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccountsReceivable
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Compensation and employee benefits

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedCompensationAndEmployeeBenefits
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCash
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Deferred Income Taxes

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentDeferredIncomeTaxes
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, goodwill, Goodwill

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillGoodwill
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssets
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Long-term deferred income taxes

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLongTermDeferredIncomeTaxes
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other long-term liabilities

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherLongTermLiabilities
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Payables

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPayables
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Prepaid expenses and other current assets

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPrepaidExpensesAndOtherCurrentAssets
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total assets acquired

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTotalAssetsAcquired
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total liabilities assumed

+ References

No definition available.

+ Details

Name:	bmi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTotalLiabilitiesAssumed
Namespace Prefix:	bmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Details

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

- Definition

The amount of inventory recognized as of the acquisition date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6910749&loc=d3e4845-128472

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 55

-Paragraph 37

-URI http://asc.fasb.org/extlink&oid=9154965&loc=d3e2207-128464

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph i

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 12, 13, 14, 20, A107

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Definition

The amount of property, plant, and equipment recognized as of the acquisition date.

+ References

+ Details

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