Line of credit facility maximum borrowing capacity sublimit.

No definition available.

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Namespace Prefix:	box_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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- 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

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Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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- Definition

This is the amount of cash advanced as security in return for borrowing securities from another party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as operating activities. This may include cash restricted for regulatory purposes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate amount of interest expense on all borrowings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ 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

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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- Details

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Balance Type:
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- Details

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Balance Type:
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Debt - Additional Information (Details) - USD ($)			1 Months Ended		3 Months Ended
Debt - Additional Information (Details) - USD ($)	Nov. 29, 2017	Nov. 27, 2017	Feb. 28, 2017	Dec. 31, 2015	Apr. 30, 2018	Apr. 30, 2017
Debt Instrument [Line Items]
Decrease in restricted cash	$ 26,100,000
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, interest expense					$ 300,000	$ 200,000
December 2015 Facility \| Revolving Credit Facility \| Secured Debt
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 40,000,000
Line of credit facility maturity date			Dec. 31, 2018	Dec. 31, 2017
Line of credit facility, floating interest rate				1.25%
Debt instrument, description of variable rate basis					The December 2015 Facility was denominated in U.S. dollars and, depending on certain conditions, each borrowing was subject to a floating interest rate equal to either the prime rate plus a spread of 0.25% to 2.75% or a reserve adjusted LIBOR rate (based on one, three or six-month interest periods) plus a spread of 1.25% to 3.75%.
Line of credit facility, commitment fee percentage				0.20%
Line of credit facility, amount drawn				$ 40,000,000
Line of credit facility, interest rate				1.82%
Repayment of outstanding principal balance		$ 40,000,000
Line of credit facility, termination date		Nov. 27, 2017
December 2015 Facility \| Revolving Credit Facility \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Minimum deposit held as collateral for line of credit				$ 0
Minimum deposit amount with lender				$ 40,000,000
December 2015 Facility \| Revolving Credit Facility \| Secured Debt \| Minimum \| Prime Rate
Debt Instrument [Line Items]
Line of credit facility, floating interest rate				0.25%
December 2015 Facility \| Revolving Credit Facility \| Secured Debt \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Line of credit facility, floating interest rate				1.25%
December 2015 Facility \| Revolving Credit Facility \| Secured Debt \| Maximum \| Prime Rate
Debt Instrument [Line Items]
Line of credit facility, floating interest rate				2.75%
December 2015 Facility \| Revolving Credit Facility \| Secured Debt \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Line of credit facility, floating interest rate				3.75%
November 2017 Facility \| Secured Debt \| Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit facility maturity date		Nov. 27, 2020
November 2017 Facility \| Revolving Credit Facility \| Secured Debt \| Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 85,000,000
Line of credit facility, interest payment terms					Interest on the revolving loans is payable quarterly in arrears with respect to loans based on the prime rate and at the end of an interest period in the case of loans based on the LIBOR rate (or at each three-month interval if the interest period is longer than three months).
November 2017 Facility \| Revolving Credit Facility \| Secured Debt \| Prime Rate \| Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit facility, floating interest rate		0.25%
November 2017 Facility \| Revolving Credit Facility \| Secured Debt \| London Interbank Offered Rate (LIBOR) \| Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit facility, floating interest rate		1.00%
November 2017 Facility \| Letter of Credit \| Secured Debt \| Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity sublimit		$ 30,000,000