Question: Did a Democrat or Republican win U.S. Senate in 2016?

full_context: Document 1: List of United States Senators from Nevada: Nevada was admitted to the Union on October 31, 1864. Its current senators are Democrat Catherine Cortez Masto (Class 3) and Republican Dean Heller (Class 1).
Document 2: John Ensign: John Eric Ensign (born March 25, 1958) is an American veterinarian and former politician based in Las Vegas, Nevada. He was a Congressman and United States Senator from Nevada, serving in the latter seat from January 2001 until May 2011. He resigned amid a Senate Ethics Committee investigation.
Document 3: Joe Sestak: Joseph Ambrose "Joe" Sestak Jr. (born December 12, 1951) is an American politician and retired U.S. Navy officer. A member of the Democratic Party, he represented Pennsylvania 's 7 congressional district in the United States House of Representatives from 2007 to 2011 and was the Democratic nominee for the United States Senate in 2010, losing to Republican nominee Pat Toomey. A two-star admiral, he was the highest-ranking military official ever elected to the United States Congress at the time of his election.
Document 4: Joe Heck: Joseph John “Joe” Heck (born October 30, 1961) is an American politician, physician, and U.S. Army Brigadier General who had served as the U.S. Representative for Nevada's 3rd congressional district from 2011 to 2017. Heck, a member of the Republican Party, is a board-certified physician and served as a Nevada State Senator from 2004-08. He ran unsuccessfully against Democrat Catherine Cortez Masto in the general election for the open Nevada United States Senate seat in 2016. In the same year, Heck made headlines by joining a long list of Republicans who opposed the GOP nominee for President, Donald Trump.
Document 5: United States Senate election in Nevada, 2012: The 2012 United States Senate election in Nevada was held on Tuesday, November 6, 2012, alongside 33 other elections to the United States Senate in other states, as well as elections to the United States House of Representatives, and the 2012 United States presidential election. The primary election was held June 12, 2012. Incumbent Republican U.S. Senator Dean Heller, who was recently appointed to this seat left vacant by resigning U.S. Senator John Ensign, was narrowly elected to his first full term over Congresswoman Shelley Berkley.
Document 6: Dean Heller: Dean Arthur Heller (born May 10, 1960) is the senior United States Senator from Nevada and a member of the Republican Party. He was elected in Nevada to that state's open U.S. Senate seat in 2012.
Document 7: Joseph Kenney: Joseph D. "Joe" Kenney (born July 12, 1960) is an American politician and member of the Republican Party who represents District 1 of the Executive Council of New Hampshire. He previously served as a member of the New Hampshire Senate, representing the 3rd District from 2003 to 2009, and as a member of the New Hampshire House of Representatives from 1995 until 2003.
Document 8: Shirley Breeden: Shirley Breeden is a Democratic member of the Nevada Senate, representing Clark County District 5 (map) since 2009. She won her first term in 2008, when she narrowly upset incumbent Republican Joe Heck.
Document 9: Catherine Cortez Masto: Catherine Marie Cortez Masto (born March 29, 1964) is an American attorney and politician who is the junior United States Senator from Nevada. She is a member of the Democratic Party. She previously served as the 32nd Attorney General of Nevada from 2007 to 2015.
Document 10: Nevada gubernatorial election, 2006: The 2006 Nevada gubernatorial election was held on November 7, 2006. Incumbent Governor Kenny Guinn could not run due to term limits. Republican Congressman Jim Gibbons defeated Democratic State Senator Dina Titus.
Document 11: Brad Wenstrup: Brad Robert Wenstrup (born June 17, 1958) is an American politician, Army Reserve officer, and Doctor of Podiatric Medicine, who has been the U.S. Representative for Ohio 's 2 congressional district since 2013. A Republican, he defeated U.S. Representative Jean Schmidt in the 2012 Republican primary election and Democrat William R. Smith in the 2012 general election. Wenstrup is a colonel in the U.S. Army Reserve and an Iraq War veteran. After the shooting of Congressman Steve Scalise on the morning of June 14, 2017, Wenstrup attended to the wounded congressman until he was transported to MedStar Washington Hospital Center.
Document 12: John Hoeven: John Henry Hoeven III (born March 13, 1957) is an American politician and the senior United States Senator from North Dakota, in office since 2011. A member of the North Dakota Republican Party, he previously served as the 31st Governor of North Dakota from December 2000 to December 2010. Hoeven was elected to the U.S. Senate in the November 2, 2010 general election. He replaced junior Senator Byron L. Dorgan, who chose not to seek re-election. Hoeven became the senior Senator in 2013 after Kent Conrad retired and was replaced by Heidi Heitkamp, who was once Hoeven's opponent for the Governor's office.
Document 13: Jeff Flake: Jeffry Lane Flake (born December 31, 1962) is an American politician and member of the Republican Party who since 2013 has served as the Junior United States Senator from Arizona alongside former 2008 presidential nominee John McCain.
Document 14: Steven Horsford: Steven Alexander Horsford (born April 29, 1973) is an American politician who was the United States Representative for Nevada's 4th congressional district from 2013 to 2015. Horsford previously served in the Nevada Senate, representing Clark County's 4th Senate District from 2005 to 2012. He also served as Nevada's first African-American state senate Majority Leader and was the first African American to represent Nevada in Congress. He is a member of the Democratic Party.
Document 15: Sharron Angle: Sharron Elaine Angle (born Sharron Elaine Ott; July 26, 1949) is an American politician who served as a Republican member of the Nevada Assembly from 1999 to 2007. She ran unsuccessfully as the 2010 Republican nominee for the U.S. Senate seat in Nevada, garnering 45 percent of the vote. On September 15, 2013 she was unanimously elected the fifth President of the National Federation of Republican Assemblies, and resigned in 2016 to run again for the Nevada U.S. Senator position being vacated by Harry Reid but failed to win the Republican primary.
ground_truth: Democrat