Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000003499-21-000005-index-headers.html | 2021-02-16 08:14:29 | |
| 0000003499-21-000005-index.html | 2021-02-16 08:14:29 | |
| 0000003499-21-000005.txt | 2021-02-16 08:14:29 | |
 0000003499-21-000005-xbrl.zip | 369634 | 2021-02-16 08:14:29 |
| alx-20201231.htm | 1998763 | 2021-02-16 08:14:29 |
| alx-20201231.xsd | 59253 | 2021-02-16 08:14:29 |
| alx-20201231_cal.xml | 71975 | 2021-02-16 08:14:29 |
| alx-20201231_def.xml | 299703 | 2021-02-16 08:14:29 |
 alx-20201231_g1.jpg | 35948 | 2021-02-16 08:14:29 |
| alx-20201231_htm.xml | 1134135 | 2021-02-16 08:14:29 |
| alx-20201231_lab.xml | 672664 | 2021-02-16 08:14:29 |
| alx-20201231_pre.xml | 454758 | 2021-02-16 08:14:29 |
| exhibit1053.htm | 48444 | 2021-02-16 08:14:29 |
| exhibit21-10k12312020.htm | 15354 | 2021-02-16 08:14:29 |
| exhibit23-10k12312020.htm | 2511 | 2021-02-16 08:14:29 |
| exhibit311-10k12312020.htm | 9140 | 2021-02-16 08:14:29 |
| exhibit312-10k12312020.htm | 8890 | 2021-02-16 08:14:29 |
| exhibit321-10k12312020.htm | 5878 | 2021-02-16 08:14:29 |
| exhibit322-10k12312020.htm | 5532 | 2021-02-16 08:14:29 |
| exhibit4-10k12312020.htm | 32319 | 2021-02-16 08:14:29 |
| FilingSummary.xml | 36995 | 2021-02-16 08:14:29 |
| Financial_Report.xlsx | 89987 | 2021-02-16 08:14:29 |
| MetaLinks.json | 668370 | 2021-02-16 08:14:29 |
| R1.htm | 63226 | 2021-02-16 08:14:29 |
| R10.htm | 4544 | 2021-02-16 08:14:29 |
| R11.htm | 14214 | 2021-02-16 08:14:29 |
| R12.htm | 7707 | 2021-02-16 08:14:29 |
| R13.htm | 39988 | 2021-02-16 08:14:29 |
| R14.htm | 24473 | 2021-02-16 08:14:29 |
| R15.htm | 23770 | 2021-02-16 08:14:29 |
| R16.htm | 5623 | 2021-02-16 08:14:29 |
| R17.htm | 7745 | 2021-02-16 08:14:29 |
| R18.htm | 35722 | 2021-02-16 08:14:29 |
| R19.htm | 37953 | 2021-02-16 08:14:29 |
| R2.htm | 85409 | 2021-02-16 08:14:29 |
| R20.htm | 46069 | 2021-02-16 08:14:29 |
| R21.htm | 6887 | 2021-02-16 08:14:29 |
| R22.htm | 12977 | 2021-02-16 08:14:29 |
| R23.htm | 11715 | 2021-02-16 08:14:29 |
| R24.htm | 22208 | 2021-02-16 08:14:29 |
| R25.htm | 102648 | 2021-02-16 08:14:29 |
| R26.htm | 44846 | 2021-02-16 08:14:29 |
| R27.htm | 18181 | 2021-02-16 08:14:29 |
| R28.htm | 23805 | 2021-02-16 08:14:29 |
| R29.htm | 16032 | 2021-02-16 08:14:29 |
| R3.htm | 23006 | 2021-02-16 08:14:29 |
| R30.htm | 38305 | 2021-02-16 08:14:29 |
| R31.htm | 35623 | 2021-02-16 08:14:29 |
| R32.htm | 19438 | 2021-02-16 08:14:29 |
| R33.htm | 21770 | 2021-02-16 08:14:29 |
| R34.htm | 54449 | 2021-02-16 08:14:29 |
| R35.htm | 28880 | 2021-02-16 08:14:29 |
| R36.htm | 20563 | 2021-02-16 08:14:29 |
| R37.htm | 39209 | 2021-02-16 08:14:29 |
| R38.htm | 22817 | 2021-02-16 08:14:29 |
| R39.htm | 9873 | 2021-02-16 08:14:29 |
| R4.htm | 50857 | 2021-02-16 08:14:29 |
| R40.htm | 51631 | 2021-02-16 08:14:29 |
| R41.htm | 14429 | 2021-02-16 08:14:29 |
| R42.htm | 11593 | 2021-02-16 08:14:29 |
| R43.htm | 7465 | 2021-02-16 08:14:29 |
| R44.htm | 51637 | 2021-02-16 08:14:29 |
| R45.htm | 36586 | 2021-02-16 08:14:29 |
| R46.htm | 17232 | 2021-02-16 08:14:29 |
| R47.htm | 20513 | 2021-02-16 08:14:29 |
| R48.htm | 14257 | 2021-02-16 08:14:29 |
| R49.htm | 25084 | 2021-02-16 08:14:29 |
| R5.htm | 6528 | 2021-02-16 08:14:29 |
| R50.htm | 14705 | 2021-02-16 08:14:29 |
| R51.htm | 20976 | 2021-02-16 08:14:29 |
| R52.htm | 20529 | 2021-02-16 08:14:29 |
| R53.htm | 25398 | 2021-02-16 08:14:29 |
| R54.htm | 23766 | 2021-02-16 08:14:29 |
| R55.htm | 52866 | 2021-02-16 08:14:29 |
| R56.htm | 9445 | 2021-02-16 08:14:29 |
| R57.htm | 4886 | 2021-02-16 08:14:29 |
| R58.htm | 27839 | 2021-02-16 08:14:29 |
| R59.htm | 108600 | 2021-02-16 08:14:29 |
| R6.htm | 18682 | 2021-02-16 08:14:29 |
| R60.htm | 27862 | 2021-02-16 08:14:29 |
| R7.htm | 36852 | 2021-02-16 08:14:29 |
| R8.htm | 4626 | 2021-02-16 08:14:29 |
| R9.htm | 92035 | 2021-02-16 08:14:29 |
| R9999.htm | 12009 | 2021-02-16 08:14:29 |
| report.css | 2767 | 2021-02-16 08:14:29 |
| Show.js | 1085 | 2021-02-16 08:14:29 |