Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0001280600-20-000012-index-headers.html | 2020-02-27 16:13:40 | |
| 0001280600-20-000012-index.html | 2020-02-27 16:13:40 | |
| 0001280600-20-000012.txt | 2020-02-27 16:13:40 | |
 0001280600-20-000012-xbrl.zip | 489195 | 2020-02-27 16:13:40 |
| FilingSummary.xml | 42815 | 2020-02-27 16:13:40 |
| Financial_Report.xlsx | 102883 | 2020-02-27 16:13:40 |
| MetaLinks.json | 671551 | 2020-02-27 16:13:40 |
 pipeline2020a01.jpg | 93677 | 2020-02-27 16:13:40 |
| R1.htm | 58919 | 2020-02-27 16:13:40 |
| R10.htm | 20019 | 2020-02-27 16:13:40 |
| R11.htm | 16980 | 2020-02-27 16:13:40 |
| R12.htm | 61204 | 2020-02-27 16:13:40 |
| R13.htm | 17251 | 2020-02-27 16:13:40 |
| R14.htm | 22375 | 2020-02-27 16:13:40 |
| R15.htm | 9250 | 2020-02-27 16:13:40 |
| R16.htm | 16161 | 2020-02-27 16:13:40 |
| R17.htm | 53245 | 2020-02-27 16:13:40 |
| R18.htm | 85665 | 2020-02-27 16:13:40 |
| R19.htm | 6545 | 2020-02-27 16:13:40 |
| R2.htm | 72778 | 2020-02-27 16:13:40 |
| R20.htm | 58352 | 2020-02-27 16:13:40 |
| R21.htm | 34482 | 2020-02-27 16:13:40 |
| R22.htm | 6670 | 2020-02-27 16:13:40 |
| R23.htm | 43759 | 2020-02-27 16:13:40 |
| R24.htm | 189161 | 2020-02-27 16:13:40 |
| R25.htm | 107089 | 2020-02-27 16:13:40 |
| R26.htm | 19135 | 2020-02-27 16:13:40 |
| R27.htm | 30218 | 2020-02-27 16:13:40 |
| R28.htm | 60457 | 2020-02-27 16:13:40 |
| R29.htm | 16889 | 2020-02-27 16:13:40 |
| R3.htm | 18851 | 2020-02-27 16:13:40 |
| R30.htm | 23195 | 2020-02-27 16:13:40 |
| R31.htm | 10513 | 2020-02-27 16:13:40 |
| R32.htm | 77102 | 2020-02-27 16:13:40 |
| R33.htm | 43796 | 2020-02-27 16:13:40 |
| R34.htm | 26505 | 2020-02-27 16:13:40 |
| R35.htm | 43919 | 2020-02-27 16:13:40 |
| R36.htm | 37225 | 2020-02-27 16:13:40 |
| R37.htm | 47591 | 2020-02-27 16:13:40 |
| R38.htm | 9773 | 2020-02-27 16:13:40 |
| R39.htm | 7954 | 2020-02-27 16:13:40 |
| R4.htm | 46756 | 2020-02-27 16:13:40 |
| R40.htm | 15612 | 2020-02-27 16:13:40 |
| R41.htm | 24189 | 2020-02-27 16:13:40 |
| R42.htm | 11954 | 2020-02-27 16:13:40 |
| R43.htm | 9279 | 2020-02-27 16:13:40 |
| R44.htm | 42613 | 2020-02-27 16:13:40 |
| R45.htm | 17290 | 2020-02-27 16:13:40 |
| R46.htm | 9533 | 2020-02-27 16:13:40 |
| R47.htm | 24743 | 2020-02-27 16:13:40 |
| R48.htm | 20020 | 2020-02-27 16:13:40 |
| R49.htm | 69650 | 2020-02-27 16:13:40 |
| R5.htm | 59959 | 2020-02-27 16:13:40 |
| R50.htm | 52325 | 2020-02-27 16:13:40 |
| R51.htm | 84361 | 2020-02-27 16:13:40 |
| R52.htm | 43072 | 2020-02-27 16:13:40 |
| R53.htm | 67562 | 2020-02-27 16:13:40 |
| R54.htm | 10396 | 2020-02-27 16:13:40 |
| R55.htm | 14752 | 2020-02-27 16:13:40 |
| R56.htm | 38806 | 2020-02-27 16:13:40 |
| R57.htm | 31348 | 2020-02-27 16:13:40 |
| R58.htm | 6337 | 2020-02-27 16:13:40 |
| R59.htm | 33082 | 2020-02-27 16:13:40 |
| R6.htm | 4415 | 2020-02-27 16:13:40 |
| R60.htm | 22713 | 2020-02-27 16:13:40 |
| R61.htm | 24003 | 2020-02-27 16:13:40 |
| R62.htm | 32473 | 2020-02-27 16:13:40 |
| R63.htm | 15734 | 2020-02-27 16:13:40 |
| R64.htm | 6752 | 2020-02-27 16:13:40 |
| R65.htm | 16898 | 2020-02-27 16:13:40 |
| R66.htm | 12471 | 2020-02-27 16:13:40 |
| R67.htm | 17692 | 2020-02-27 16:13:40 |
| R7.htm | 67201 | 2020-02-27 16:13:40 |
| R8.htm | 6098 | 2020-02-27 16:13:40 |
| R9.htm | 161411 | 2020-02-27 16:13:40 |
| R9999.htm | 11832 | 2020-02-27 16:13:40 |
| report.css | 2767 | 2020-02-27 16:13:40 |
| Show.js | 1085 | 2020-02-27 16:13:40 |
 totalreturnchart2019.jpg | 37887 | 2020-02-27 16:13:40 |
| xlrn-20191231.xsd | 59562 | 2020-02-27 16:13:40 |
| xlrn-20191231x10k.htm | 2473279 | 2020-02-27 16:13:40 |
| xlrn-20191231x10k_htm.xml | 1709099 | 2020-02-27 16:13:40 |
| xlrn-20191231xex1019.htm | 36500 | 2020-02-27 16:13:40 |
| xlrn-20191231xex1021.htm | 31637 | 2020-02-27 16:13:40 |
| xlrn-20191231xex1022.htm | 54812 | 2020-02-27 16:13:40 |
| xlrn-20191231xex211.htm | 4086 | 2020-02-27 16:13:40 |
| xlrn-20191231xex231.htm | 9771 | 2020-02-27 16:13:40 |
| xlrn-20191231xex311.htm | 12930 | 2020-02-27 16:13:40 |
| xlrn-20191231xex312.htm | 12910 | 2020-02-27 16:13:40 |
| xlrn-20191231xex321.htm | 10159 | 2020-02-27 16:13:40 |
| xlrn-20191231xex44.htm | 26140 | 2020-02-27 16:13:40 |
| xlrn-20191231_cal.xml | 89950 | 2020-02-27 16:13:40 |
| xlrn-20191231_def.xml | 304477 | 2020-02-27 16:13:40 |
| xlrn-20191231_lab.xml | 796154 | 2020-02-27 16:13:40 |
| xlrn-20191231_pre.xml | 491453 | 2020-02-27 16:13:40 |