Fair Value Measurements - Additional Information (Details)	3 Months Ended
Mar. 31, 2016 USD ($)
Fair Value Disclosures [Abstract]
Transfer between fair value measurement levels	$ 0

Transfers of financial instruments between levels.

No definition available.

Name:	mb_TransfersOfFinancialInstrumentsBetweenLevels
Namespace Prefix:	mb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration