The fee payable, expressed as a percent, on total loan advances on a debt instrument.

No definition available.

Name:	bpmc_DebtInstrumentFeePayableOnTotalLoanAdvancesPercentage
Namespace Prefix:	bpmc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of tranches or structured financing of the debt agreement.

+ References

No definition available.

+ Details

Name:	bpmc_DebtInstrumentNumberOfTranches
Namespace Prefix:	bpmc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The prepayment fee, expressed as a percent, on outstanding principal at the time prepayment on a debt instrument, high end of range.

+ References

No definition available.

+ Details

Name:	bpmc_DebtInstrumentPrepaymentFeePercentageHighEndOfRange
Namespace Prefix:	bpmc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The prepayment fee, expressed as a percent, on outstanding principal at the time prepayment on a debt instrument, low end of range.

+ References

No definition available.

+ Details

Name:	bpmc_DebtInstrumentPrepaymentFeePercentageLowEndOfRange
Namespace Prefix:	bpmc_
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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The cash inflow from bank borrowing during the year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=bpmc_TermLoan2013Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=bpmc_TermLoan2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Term Loan - General Information (Details) - Secured Debt $ in Millions	1 Months Ended
	Nov. 30, 2014 USD ($)	May 31, 2013 USD ($) tranche	Jun. 30, 2018
2013 Term Loan
Term Loan
Face amount		$ 5.0
Number of tranches \| tranche		3
2013 Term Loan \| Prime Rate
Term Loan
Fixed rate based on percentage points added to base rate (as a percent)		2.00%
2014 Term Loan
Term Loan
Face amount	$ 5.0
Proceeds from term loan	$ 5.0
Percentage fee payable on total loan advances at end of loan (as a percent)			4.00%
Percentage fee payable on outstanding principal in event of prepayment of loan advances, low end of range (as a percent)			1.00%
Percentage fee payable on outstanding principal in event of prepayment of loan advances, high end of range (as a percent)			2.00%