Addressing many of the world's contemporary challenges requires a multifaceted and integrated approach and, in this respect, interdisciplinary research (IDR) is increasingly recognized as central to both academic interests and national science policies. In spite of the growing attention given to IDR, the impact of IDR remains under-investigated. In this study, we analyzed the influence of interdisciplinarity on citation impact (particularly, WoS citation) and broader impact (particularly, PloS usage) at the article level. We measured IDR in terms of three different elements of diversity-variety, balance, and disparity--as well as the integrated diversity overall. The results of negative binomial regression analysis with field fixed effects and robust standard errors show the positive effects of interdisciplinarity on both academic and broader impact. From an analysis of trends over time, the results show that higher interdisciplinary publications tend to attract more citations and have higher PLoS usage. Compared to citations, which need a more extended period to accumulate, the advantage of measuring impact with PLoS usage is its immediacy. Also, there are signs that PLoS usage and citations can mutually reinforce each other.