 
Idaho Amendment 2 of 2006 is an amendment to the Idaho Constitution that made it unconstitutional for the state to recognize or perform same-sex marriages or civil unions.
The text of the amendment states:
"A marriage between a man and a woman is the only domestic legal union that shall be valid or recognized in this state."
The amendment was passed 53–17 by the Idaho House of Representatives on February 6, 2006, and 26–9 by the Idaho Senate on February 15, 2006. It was subsequently approved by 63% of voters in a referendum.
On May 13, 2014, a United States magistrate judge struck down Amendment 2 as unconstitutional, but enforcement of that ruling was stayed pending appeal. The Ninth Circuit Court of Appeals affirmed that ruling on October 7, 2014, though the U.S. Supreme Court issued a stay of the ruling, which was not lifted until October 15, 2014.
On June 26, 2015, the United States Supreme Court ruled in "Obergefell v. Hodges" that state bans on same-sex marriage violated the 14th Amendment's guarantees of Equal Protection and Due Process, making same-sex marriage permanently legal in Idaho.
Result.
Results by county.
Source: Idaho Secretary of State