  The Integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in
the Cosmic Microwave Background due to time variation of the gravitational
potential when the expansion of the universe is not matter dominated. The ISW
effect is therefore expected in the early universe, due to the presence of
relativistic particles at recombination, and in the late universe, when dark
energy starts to dominate the expansion. Deviations from the standard picture
can be parameterized by $A_{e\text{ISW}}$ and $A_{l\text{ISW}}$, which rescale
the overall amplitude of the early and late ISW effects. Analyzing the most
recent CMB temperature spectra from the Planck 2015 release, we detect the
presence of the early ISW at high significance with $A_{e\mathrm{ISW}} =
1.06\pm0.04$ at 68% CL and an upper limit for the late ISW of
$A_{l\mathrm{ISW}} < 1.1$ at 95% CL. The inclusion of the recent polarization
data from the Planck experiment results in $A_{e\mathrm{ISW}} = 0.999\pm0.028$
at 68% CL, in better agreement with the value $A_{e\mathrm{ISW}} = 1$ of a
standard cosmology. When considering the recent detections of the late ISW
coming from correlations between CMB temperature anisotropies and weak lensing,
a value of $A_{l\mathrm{ISW}}=0.85\pm0.21$ is predicted at 68% CL, showing a
$4\sigma$ evidence. We discuss the stability of our result in the case of an
extra relativistic energy component parametrized by the effective neutrino
number $N_\mathrm{eff}$ and of a CMB lensing amplitude $A_\mathrm{L}$.
