Real Estate Owned (Details)	Dec. 31, 2012
Property, Plant And Equipment [Line Items]
Number of commercial office building owned	1
Area of office building (in square feet)	14,500
Area of office building utilized for executive offices (in square feet)	3,500

Area of office building utilized for executive offices.

No definition available.

Name:	abcp_AreaOfOfficeBuildingUtilizedForExecutiveOffices
Namespace Prefix:	abcp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant