Algebraic number theory introduces students to new algebraic notions as well as related concepts: groups, rings, fields, ideals, quotient rings, and quotient fields. This text covers the basics, from divisibility theory in principal ideal domains to the unit theorem, finiteness of the class number, and Hilbert ramification theory. 1970 edition.
This is a great approach to teaching Algebraic Number Theory. It may be a bit difficult for beginners, and I think it is best read while reading a text with a more computational and concrete approach.