XML 67 R26.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Significant accounting policies (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2011
Accounting Policies [Abstract] |
Reconciliation Of Net Income Attributable To Common Stockholders To Estimated Taxable Income [Table Text Block] |
| (Unaudited and in thousands) | Years Ended December 31, |  |
|  | 2011 |  | 2010 |  | 2009 |  |
| Net income attributable to Alexander’s | $ | 79,423 |  | $ | 66,429 |  | $ | 132,190 |  |
| Straight-line rent adjustments |  | (12,609) |  |  | (15,182) |  |  | (23,381) |  |
| Depreciation and amortization timing differences |  | 1,263 |  |  | 602 |  |  | 1,385 |  |
| Reversal of liability for income taxes |  | - |  |  | (3,162) |  |  | (37,307) |  |
| Interest expense |  | (2,425) |  |  | - |  |  | (107) |  |
| Stock appreciation rights compensation expense |  | - |  |  | - |  |  | (57,113) |  |
| Other |  | (3,429) |  |  | 6,245 |  |  | (3,395) |  |
| Taxable income before net operating loss ("NOL") |  | 62,223 |  |  | 54,932 |  |  | 12,272 |  |
| NOL carried forward |  | - |  |  | (16,939) |  |  | (29,211) |  |
| Estimated taxable income/(loss) | $ | 62,223 |  | $ | 37,993 |  | $ | (16,939) |  |

X
- Definition Table reconciling net income attributable to common stockholders to estimated taxable income + References No definition available. + Details
Name: | alx_ReconciliationOfNetIncomeAttributableToCommonShareholdersToEstimatedTaxableIncomeTableTextBlock
Namespace Prefix: | alx_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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