Stockholder Rights Plan - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Portion of preferred share purchase right entitled to holder	0.0001
Purchase price of Preferred Stock as per plan	$ 150.00
Number of votes entitled to common stock	One
Price worth of surviving company common stock	300.00
Percentage common stock to acquired to exercise stock rights	20.00%
Redemption price of stock holder rights plan	$ 0.01
Percentage of beneficial ownership	20.00%bdc_PercentageOfBeneficialOwnership

Class Of Warrant Or Right Value Of Stock Common Stock Acquired Upon Exercise

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- Definition

Percentage common stock to acquired to exercise stock rights.

+ References

No definition available.

+ Details

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- Definition

Percentage of beneficial ownership.

+ References

No definition available.

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- Definition

Redemption price of Stock holder rights plan.

+ References

No definition available.

+ Details

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(i)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Subparagraph 2

-Article 4

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- Definition

Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

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