diff --git a/src/BelongsToMany.php b/src/BelongsToMany.php
index 15e0a4e..425e5dd 100644
--- a/src/BelongsToMany.php
+++ b/src/BelongsToMany.php
@@ -105,7 +105,7 @@ public function attach($id, array $attributes = [], $touch = true)
     public function detach($ids = null, $touch = true)
     {
         // Get detached ids to pass them to event
-        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck('id');
+        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck($this->relatedKey);
 
         $this->parent->fireModelBelongsToManyEvent('detaching', $this->getRelationName(), $ids);
 
diff --git a/src/MorphToMany.php b/src/MorphToMany.php
index 3ebe448..e3628f8 100644
--- a/src/MorphToMany.php
+++ b/src/MorphToMany.php
@@ -103,7 +103,7 @@ public function attach($id, array $attributes = [], $touch = true)
     public function detach($ids = null, $touch = true)
     {
         // Get detached ids to pass them to event
-        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck('id');
+        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck($this->relatedKey);
 
         $this->parent->fireModelMorphToManyEvent('detaching', $this->getRelationName(), $ids);
 
diff --git a/src/MorphedByMany.php b/src/MorphedByMany.php
index b932b39..e7303c7 100644
--- a/src/MorphedByMany.php
+++ b/src/MorphedByMany.php
@@ -103,7 +103,7 @@ public function attach($id, array $attributes = [], $touch = true)
     public function detach($ids = null, $touch = true)
     {
         // Get detached ids to pass them to event
-        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck('id');
+        $ids = $ids ?? $this->parent->{$this->getRelationName()}->pluck($this->relatedKey);
 
         $this->parent->fireModelMorphedByManyEvent('detaching', $this->getRelationName(), $ids);