The major news networks are a poor source of news, and they are not truly ideological (except for the ideology about maximizing profits). Fox News is "conservative" because a panel of business people sits around discussing how to keep their audience, which consists on average of 70 year old conservatives, watching the network. If shouting about Obama keeps their audience engaged, and enraged, then that's what they'll do. But it isn't sincere. It's just a business decision. Fox having captured the old-white-men-who-watch-TV-news market, CNN fights for whatever is left (TV screens at the gym? Who the **** actually watches that trash?).
Print media is mostly "liberal" leaning because journalists, who are formally educated city-dwellers, tend to be more liberal. So the news comes from that perspective. WSJ editorial pages tend to lean conservative, specially economically, but the rest of the paper still reflects the liberalist perspective.