The abbreviation for the Latin phrase id est should not be italicised in normal usage.
From the en.wikipedia.org
Moreover, meat production rose from 14.0 million tons in 1971-75 to 19.2 million tons in 1986-89, id est, a 37% increase.
From the en.wikipedia.org
Nec quicquam notabile in singulis, nisi quod in commune Nerthum, id est Terram matrem, colunt eamque intervenire rebus hominum, invehi populis arbitrantur.
From the en.wikipedia.org
Mauris elementum, sem id laoreet auctor, lacus dui dictum est, ultrices auctor risus orci at enim.