XML 70 R55.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Schedule III: Real Estate and Accumulated Depreciation (Rollforward of Real Estate and Accumulated Deprecation) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
REAL ESTATE: |  |  |
Balance at beginning of period | $ 1,033,551 | $ 1,029,472 | $ 993,927
Subtotal real estate | 1,037,368 | 1,035,230 | 1,040,662
Less: Fully depreciated assets | 0 | (1,679) | (11,190)
Balance at end of the period | 1,037,368 | 1,033,551 | 1,029,472
ACCUMULATED DEPRECIATION: |  |  |
Balance at beginning of period | 252,737 | 225,533 | 210,025
Additions charged to operating expenses | 30,307 | 28,883 | 26,698
Subtotal of accumulated depreciation | 283,044 | 254,416 | 236,723
Less: Fully depreciated assets | 0 | (1,679) | (11,190)
Balance at end of the period | 283,044 | 252,737 | 225,533
Land |  |  |
REAL ESTATE: |  |  |
Changes during the period | 0 | 0 | 0
Buildings and leasehold improvements |  |  |
REAL ESTATE: |  |  |
Changes during the period | 3,046 | 12,464 | 112,538
Development and construction in progress |  |  |
REAL ESTATE: |  |  |
Changes during the period | $ 771 |  |
Changes during the period |  | $ (6,706) | $ (65,803)

X
- Definition The subtotal of accumulated depreciation balance excluding accumulated depreciation on assets sold and write-off of accumulated depreciation on fully depreciated assets. + References No definition available. + Details
Name: | alx_RealEstateAccumulatedDepreciationBeforeAccumulatedDepreciationOnAssetSoldAndWrittenOff
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The subtotal of real estate asset balance excluding assets sold and write-off of fully depreciated assets. + References No definition available. + Details
Name: | alx_RealEstateBeforeRealEstateSoldAndWrittenOff
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of other additions to accumulated depreciation other than depreciation expense for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationOtherAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of decrease to accumulated depreciation for real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateCostOfRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, before accumulated depreciation, of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateGrossAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase in real estate investments related to improvements for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of other deductions to real estate investments, excluding sales, for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateOtherDeductions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=us-gaap_LandImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=us-gaap_BuildingImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=us-gaap_ConstructionInProgressMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |