Debt Instrument, Interest Rate Floor

No definition available.

Name:	bel_DebtInstrumentInterestRateFloor
Namespace Prefix:	bel_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Mandatory Amortization, Percentage

+ References

No definition available.

+ Details

Name:	bel_DebtInstrumentMandatoryAmortizationPercentage
Namespace Prefix:	bel_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585

Reference 3: 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.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=bel_TrancheOneTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bel_TrancheTwoTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=bel_EuriborMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
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Subsequent events (Details) € in Thousands			3 Months Ended	6 Months Ended
Subsequent events (Details) € in Thousands	Jul. 03, 2017 USD ($)	May 26, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jul. 03, 2017 EUR (€)	Jun. 30, 2017 EUR (€)
Subsequent Event [Line Items]
Debt instrument, face amount				$ 499,569,000
Proceeds from credit facility		$ 45,000,000	$ 0	$ 45,000,000	$ 0
Tranche One term loan \| LIBOR
Subsequent Event [Line Items]
Basis spread on variable interest rate				3.00%
Tranche Two term loan \| EURIBOR
Subsequent Event [Line Items]
Basis spread on variable interest rate				3.00%
Secured Credit Facility
Subsequent Event [Line Items]
Debt instrument, term				7 years
Debt instrument, face amount				$ 551,955,000
Secured Credit Facility \| Tranche One term loan
Subsequent Event [Line Items]
Debt instrument, face amount				345,000,000
Secured Credit Facility \| Tranche Two term loan
Subsequent Event [Line Items]
Debt instrument, face amount				206,955,000			€ 150,000
Revolving Credit Facility
Subsequent Event [Line Items]
Debt instrument, face amount				$ 105,000,000
Subsequent Event \| Secured Credit Facility
Subsequent Event [Line Items]
Debt instrument, face amount	$ 603,434,000
Subsequent Event \| Secured Credit Facility \| Tranche One term loan
Subsequent Event [Line Items]
Debt instrument, face amount	$ 400,000,000
Debt instrument, interest rate floor	0.00%					0.00%
Subsequent Event \| Secured Credit Facility \| Tranche One term loan \| LIBOR
Subsequent Event [Line Items]
Basis spread on variable interest rate	2.75%
Debt instrument mandatory amortization percentage	1.00%					1.00%
Subsequent Event \| Secured Credit Facility \| Tranche Two term loan
Subsequent Event [Line Items]
Debt instrument, face amount	$ 203,434,000					€ 179,000
Debt instrument, interest rate floor	0.00%					0.00%
Subsequent Event \| Secured Credit Facility \| Tranche Two term loan \| EURIBOR
Subsequent Event [Line Items]
Basis spread on variable interest rate	3.00%
Subsequent Event \| Revolving Credit Facility
Subsequent Event [Line Items]
Debt instrument, face amount	$ 100,000,000
Subsequent Event \| Revolving Credit Facility \| Tranche One term loan \| LIBOR
Subsequent Event [Line Items]
Basis spread on variable interest rate	2.50%
Commitment fee	0.40%