$117 million opening weekend
http://www.boxofficemojo.com/news/?id=4323&p=.htm
2nd largest opening for an R-Rated movie ever, just behind Deadpool (132 million) and definitely the largest for a horror film ever. I think it will have legs, I'm not sure for how long -- but good word of mouth + lack of good cinema options lately are likely to help IT. With a budget of $35 million (and assuming marketing costs were also around that), this film is a big hit for WB, however much it further makes.