As of the census of 2000, there were 112,646 people, 43,545 households, and 29,915 families residing in the county. The population density was 219 people per square mile (85/km²). There were 45,947 housing units at an average density of 90 per square mile (35/km²). The racial makeup of the county was 92.71% White, 1.09% Black or African American, 0.36% Native American, 3.28% Asian, 0.02% Pacific Islander, 1.46% from other races, and 1.07% from two or more races. 3.36% of the population were Hispanic or Latino of any race. 54.9% were of German, 7.8% Dutch and 5.4% American ancestry. 91.9% spoke English, 3.0% Spanish, 2.5% Hmong and 1.7% German as their first language.
There were 43,545 households out of which 32.30% had children under the age of 18 living with them, 58.00% were married couples living together, 7.30% had a female householder with no husband present, and 31.30% were non-families. 26.10% of all households were made up of individuals and 10.40% had someone living alone who was 65 years of age or older. The average household size was 2.50 and the average family size was 3.05.
In the county, the population was spread out with 25.50% under the age of 18, 8.40% from 18 to 24, 29.80% from 25 to 44, 22.30% from 45 to 64, and 14.00% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 100.60 males. For every 100 females age 18 and over, there were 99.90 males.