Document And Entity Information (USD $)	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Entity Registrant Name	AMBASE Corp
Entity Central Index Key	0000020639
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float		$ 6,000,000
Entity Common Stock, Shares Outstanding	43,075,410
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2011