You're talking about LA Confidential, with the all-star cast of Kevin Spacey, Russell Crowe, Danny DeVito and Kim Basinger, among others. Academy Award for Kim Basinger and I believe the best screenplay, but nominated for plenty of other movies. Yes it was a box office hit. Curtis Handon directed, a movie or two before 8 Mile.
Based on the novel by that really under-the-radar crime novelist James Ellroy.
Yeah I'd put it pretty close to other non-blockbuster movies such as Braveheart and Dances With Wolves.