Liabilities Measured at Fair Value Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent acquisition consideration payable, Beginning balance	$ 161,637
Changes in the fair value of contingent acquisition consideration payable for continuing development programs	1,353
Foreign exchange remeasurement of Euro denominated contingent acquisition consideration payable	2,167
Contingent acquisition consideration payable, Ending balance	161,657
Huxley Pharmaceuticals, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Milestone payments to former shareholders	$ (3,500)

Fair value measurement with unobservable inputs reconciliations recurring basis foreign exchange remeasurement.

No definition available.

Name:	bmrn_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisForeignExchangeRemeasurement
Namespace Prefix:	bmrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value measurement with unobservable inputs reconciliations recurring basis milestone payments to shareholders.

+ References

No definition available.

+ Details

Name:	bmrn_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisMilestonePaymentsToShareholders
Namespace Prefix:	bmrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=bmrn_ContingentPaymentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=bmrn_HuxleyPharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: