Name:	msb_RevenueCeilingQuantityForFirstTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

The ceiling quantity for the second tier of base overriding royalties earned. Shipments up to this amount, above the first tier ceiling, are subject to the second tier portion percentage in calculating the royalties earned.

No definition available.

Name:	msb_RevenueCeilingQuantityForSecondTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

The number of volume thresholds used to determine the transaction price.

No definition available.

Name:	msb_RevenueNumberOfVolumeThresholdsForVariableTransactionPrice
Namespace Prefix:	msb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The percentage applied to the quantity shipped in the first tier, to determine the quantity on which royalties are earned.

No definition available.

Name:	msb_RevenuePortionPercentageForFirstTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The percentage applied to the quantity shipped in the second tier, to determine the quantity on which royalties are earned.

No definition available.

Name:	msb_RevenuePortionPercentageForSecondTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The percentage applied to the quantity shipped in the third tier, to determine the quantity on which royalties are earned.

No definition available.

Name:	msb_RevenuePortionPercentageForThirdTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The threshold quantity for the third tier of base overriding royalties earned. Shipments above this amount are subject to the third tier portion percentage in calculating the royalties earned.

No definition available.

Name:	msb_RevenueThresholdQuantityForThirdTierOfConsideration
Namespace Prefix:	msb_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

The quantity shipped which serves as a threshold to determine transaction price.

No definition available.

Name:	msb_RevenueVolumeThresholdForTransactionPrice
Namespace Prefix:	msb_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 3: 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(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4531-111522

Name:	us-gaap_AccountsReceivableNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130533-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerAssetNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

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

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045