as.Date.IDate won't change the class if xts package loaded #1500
Description
To convert your IDate into Date you currently need to go through as.integer.
library(data.table)
id = as.IDate("2016-01-15")
class(id)
#[1] "IDate" "Date"
class(as.Date(id))
#[1] "IDate" "Date"
class(as.Date(as.integer(id)))
#[1] "Date" when resolved update this SO.