  The SiD concept is one of two proposed detectors to be mounted at the
interaction region of the International Linear Collider (ILC). A substantial
ILC background arises from low transverse momentum
$\mathrm{e}^{+}\mathrm{e}^{-}$ pairs created by the interaction of the
colliding beams' electromagnetic fields. In order to provide hermeticity and
sensitivity to beam targeting parameters, a forward Beamline Calorimeter
(BeamCal) is being designed that will provide coverage down to 5 mrad from the
outgoing beam trajectory, and intercept the majority of this pair background.
Using the SiD simulation framework, the effect of this pair background on the
SiD detector components, especially the vertex detector (VXD) and forward
electromagnetic calorimeter (FCAL), is explored. In the case of the FCAL,
backgrounds from Bhabha and two-photon processes are also considered. The
consequence of several variants of the BeamCal geometry and ILC interaction
region configuration are considered for both the vertex detector and BeamCal
performance.
