Theres a shift in Idaho but they still voted for the R's at nearly 70%.
I grew up in Boise and left town in 85 and the state in 88. In that entire time (25 years) Idaho had a Democrat Governor and one Democrat Senator and one Democrat House Member. The legislature was taken over by Libertarians in the early 80's for a few years.
The farmers loved their subsidies and the "Agra-Dems" were the ones pushing them in those days... So... Libertarian leaning people who wanted subsidies.

In the late 70's Idaho Governor Cecil Andrus was appointed Secretary of the Interior by Carter... So Idaho wasn't always as "Red" as it is now.