diff --git a/src/cdk/overlay/overlay-ref.ts b/src/cdk/overlay/overlay-ref.ts
index d1bd5c4657b9..45f5644a6f0a 100644
--- a/src/cdk/overlay/overlay-ref.ts
+++ b/src/cdk/overlay/overlay-ref.ts
@@ -95,6 +95,10 @@ export class OverlayRef implements PortalHost {
    * @returns The portal detachment result.
    */
   detach(): any {
+    if (!this.hasAttached()) {
+      return;
+    }
+
     this.detachBackdrop();
 
     // When the overlay is detached, the pane element should disable pointer events.
@@ -122,6 +126,8 @@ export class OverlayRef implements PortalHost {
    * Cleans up the overlay from the DOM.
    */
   dispose(): void {
+    const isAttached = this.hasAttached();
+
     if (this._config.positionStrategy) {
       this._config.positionStrategy.dispose();
     }
@@ -134,7 +140,11 @@ export class OverlayRef implements PortalHost {
     this._portalHost.dispose();
     this._attachments.complete();
     this._backdropClick.complete();
-    this._detachments.next();
+
+    if (isAttached) {
+      this._detachments.next();
+    }
+
     this._detachments.complete();
   }
 
diff --git a/src/cdk/overlay/overlay.spec.ts b/src/cdk/overlay/overlay.spec.ts
index b5b35cc15ba9..b3fb79897842 100644
--- a/src/cdk/overlay/overlay.spec.ts
+++ b/src/cdk/overlay/overlay.spec.ts
@@ -177,6 +177,26 @@ describe('Overlay', () => {
     expect(spy).toHaveBeenCalled();
   });
 
+  it('should not emit to the detach stream if the overlay has not been attached', () => {
+    let overlayRef = overlay.create();
+    let spy = jasmine.createSpy('detachments spy');
+
+    overlayRef.detachments().subscribe(spy);
+    overlayRef.detach();
+
+    expect(spy).not.toHaveBeenCalled();
+  });
+
+  it('should not emit to the detach stream on dispose if the overlay was not attached', () => {
+    let overlayRef = overlay.create();
+    let spy = jasmine.createSpy('detachments spy');
+
+    overlayRef.detachments().subscribe(spy);
+    overlayRef.dispose();
+
+    expect(spy).not.toHaveBeenCalled();
+  });
+
   it('should emit the detachment event after the overlay is removed from the DOM', () => {
     let overlayRef = overlay.create();