This is the first in-depth study on the coverage of Microsoft Academic (MA). The coverage of a verified publication list of a university was analyzed on the level of individual publications in MA, Scopus, and Web of Science (WoS). Citation counts were analyzed and issues related to data retrieval and data quality were examined. A Perl script was written to retrieve metadata from MA. We find that MA covers journal articles, working papers, and conference items to a substantial extent. MA surpasses Scopus and WoS clearly with respect to book-related document types and conference items but falls slightly behind Scopus with regard to journal articles. MA shows the same biases as Scopus and WoS with regard to the coverage of the social sciences and humanities, non-English publications, and open-access publications. Rank correlations of citation counts are high between MA and the benchmark databases. We find that the publication year is correct for 89.5% of all publications and the number of authors for 95.1% of the journal articles. Given the fast and ongoing development of MA, we conclude that MA is on the verge of becoming a bibliometric superpower. However, comprehensive studies on the quality of MA data are still lacking.