XML 25 R11.htm IDEA: XBRL DOCUMENT v2.4.0.8

NET INCOME PER UNIT (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Jan. 31, 2014
NET INCOME PER UNIT
Accrued income receivable	$ 3,309,221		$ 3,309,221		$ 63,253
Number of units outstanding	13,120,010	13,120,010	13,120,010	13,120,010

X

- Definition

Royalty revenue and estimated price adjustments related to prior periods earned but not yet received by the entity on its mineral interests.

+ References

No definition available.

+ Details

Name:	msb_AccruedIncomeReceivable
Namespace Prefix:	msb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Average number of units of beneficial interests outstanding during the reporting period.

+ References

No definition available.

+ Details

Name:	msb_WeightedAverageNumberOfUnitsOutstanding
Namespace Prefix:	msb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Details

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