Basis of Presentation (Details)	3 Months Ended
Mar. 31, 2015 item
Basis of Presentation
Number of significant subsequent events	0

Represents the number of significant subsequent events, which would warrant adjustments or require disclosures in the financial statements of the entity.

No definition available.

Name:	buse_NumberOfSignificantSubsequentEvents
Namespace Prefix:	buse_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration