Group a collection and return a Dictionary

How about:

public ILookup<string, PriceDetail> GetGroupedPriceDetails(IEnumerable<PriceDetail> priceDetails)
{
     return priceDetails.ToLookup(priceDetail => priceDetail.Code);
}

Can you not do:

priceDetails.GroupBy(priceDetail => priceDetail.Code)
               .ToDictionary(group => group.Key, group => group.ToList())