XML 72 R27.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Related party transaction (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2011
Related party transactions [Abstract] |
Summary of Fees to Vornado [Table Text Block] |
(Amounts in thousands) |  | Year Ended December 31, |  |
|  |  | 2011 |  | 2010 |  | 2009 |  |
Company management fees |  | $ | 3,000 |  | $ | 3,000 |  | $ | 3,000 |  |
Development fees |  |  | 750 |  |  | 727 |  |  | 3,215 |  |
Leasing fees |  |  | 4,472 |  |  | 4,267 |  |  | 15,975 |  |
Property management fees and payments for cleaning, engineering |  |  |  |  |  |  |  |  |  |  |
| and security services |  |  | 4,648 |  |  | 4,342 |  |  | 4,108 |  |
|  |  | $ | 12,870 |  | $ | 12,336 |  | $ | 26,298 |  |

X
- Definition Summary of fees to related party under the agreements + References No definition available. + Details
Name: | alx_ScheduleOfFeesPaidToRelatedPartyUnderAgreementTableTextBlock
Namespace Prefix: | alx_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration