Condensed Consolidating Financial Information - Additional Information (Detail)	Sep. 30, 2018
Equity Method Investments And Joint Ventures [Abstract]
Percentage of ownership owned	100.00%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	mini_InvestmentOwnershipPercentage
Namespace Prefix:	mini_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant