Intangible Assets - Changes in Carrying Amount of Trademarks (Detail) (Trademarks [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Indefinite-lived Intangible Assets [Line Items]
Trademarks, Beginning Balance	$ 92,010us-gaap_IndefiniteLivedTrademarks	$ 103,347us-gaap_IndefiniteLivedTrademarks
Reclassify to definite-lived	(6,600)	(6,777)
Acquisitions and purchase accounting adjustments	22,000	(4,918)
Translation impact	(4,370)	358
Trademarks, Ending Balance	103,040us-gaap_IndefiniteLivedTrademarks	92,010us-gaap_IndefiniteLivedTrademarks
Broadcast Solutions [Member]
Indefinite-lived Intangible Assets [Line Items]
Trademarks, Beginning Balance	70,127	80,310
Reclassify to definite-lived	(2,700)	(5,424)
Acquisitions and purchase accounting adjustments	22,000	(4,918)
Translation impact	(2,244)	159
Trademarks, Ending Balance	87,183	70,127
Enterprise Connectivity Solutions [Member]
Indefinite-lived Intangible Assets [Line Items]
Trademarks, Beginning Balance		1,299
Reclassify to definite-lived		(1,353)
Translation impact		54
Industrial Connectivity Solutions [Member]
Indefinite-lived Intangible Assets [Line Items]
Trademarks, Beginning Balance	12,193	12,279
Translation impact	(1,449)	(86)
Trademarks, Ending Balance	10,744	12,193
Industrial IT Solutions [Member]
Indefinite-lived Intangible Assets [Line Items]
Trademarks, Beginning Balance	9,690	9,459
Reclassify to definite-lived	(3,900)
Translation impact	(677)	231
Trademarks, Ending Balance	$ 5,113	$ 9,690

Reclassification From Indefinite Lived Intangible Assets To Definite Lived Assets Trademarks

No definition available.

Name:	bdc_ReclassificationFromIndefiniteLivedIntangibleAssetsToDefiniteLivedAssetsTrademarks
Namespace Prefix:	bdc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase in assets, excluding financial assets and goodwill, lacking physical substance with an indefinite life, resulting from a business combination.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Amount of increase (decrease) of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit, from foreign currency translation and purchase accounting adjustments.

+ References

No definition available.

+ Details

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

- Definition

Carrying amount (original costs adjusted for previously recognized amortization and impairment) as of the balance sheet date for the rights acquired through registration of a trademark to gain or protect exclusive use of a business name, symbol or other device or style for a projected indefinite period of benefit.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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