Name:	bmch_AccountsReceivableIncludingUnbilledReceivables
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Period Type:	instant

Change in contract asset balance.

No definition available.

Name:	bmch_ContractWithCustomerAssetPeriodChange
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Change in contract liabilities balance for the period

No definition available.

Name:	bmch_ContractWithCustomerLiabilityPeriodChange
Namespace Prefix:	bmch_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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Name:	us-gaap_ContractWithCustomerAssetNetCurrent
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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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Name:	us-gaap_ContractWithCustomerLiabilityCurrent
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The increase (decrease) during the reporting period in the amount due from customers for the credit sale of goods and services; includes accounts receivable and other types of receivables.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Period Type:	duration

Amount of increase (decrease) in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_IncreaseDecreaseInContractWithCustomerAsset
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Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable.