Operating Segments (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Oct. 02, 2011	Oct. 03, 2010	Oct. 02, 2011	Oct. 03, 2010
Reported Operating Segments
External customer revenues	$ 519,713	$ 396,927	$ 1,517,592	$ 1,191,914
Operating income	51,863	41,586	152,148	112,491
Americas [Member]
Reported Operating Segments
External customer revenues	325,248	232,133	927,978	686,985
Affiliate revenues	9,919	11,735	33,462	36,605
Operating income	39,636	30,474	111,587	81,315
EMEA [Member]
Reported Operating Segments
External customer revenues	103,713	90,397	322,901	273,140
Affiliate revenues	30,795	20,707	80,943	53,330
Operating income	22,767	14,850	63,334	41,152
Asia Pacific [Member]
Reported Operating Segments
External customer revenues	90,752	74,397	266,713	231,789
Affiliate revenues	159		658	62
Operating income	6,980	8,629	22,581	22,172
Operating Segments [Member]
Reported Operating Segments
External customer revenues	519,713	396,927	1,517,592	1,191,914
Affiliate revenues	40,873	32,442	115,063	89,997
Reportable Segment [Member]
Reported Operating Segments
Operating income	$ 69,383	$ 53,953	$ 197,502	$ 144,639

Reported Operating Segments.

Name:	bdc_ReportedOperatingSegmentsAbstract
Namespace Prefix:	bdc
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ Details

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

- Definition

Amount of revenue from transactions with other operating segments of the same entity.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 1

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(a))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

Name:	us-gaap_SalesRevenueGoodsNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration