Let $R$ be a number ring and a Dedekind domain. We have the following result:
For every ideal $I\subset R$ $$ I = \bigcap_P I_P $$ where $I_P$ denotes the localization of $I$ at $P$ and the intersection is taken over all the prime ideals $P$ of $R$.
My question is: Can we deduce from this that if $I_P$ is principal in $R_P$ for every prime ideal $P$ of $R$, then $I$ itself is principal? Or stated differently, is being principal a local property?