When mentioning a source in my literature review, how much detail should I add?
The answer is that there is no universal answer to this question. 

The first key is to have a clearly defined objective to your literature review. In some cases, you might not be interested in the methods used. In other cases, you might be.

Second, your references need to support the point you're making. Again, the level of details will vary.

Reporting every little details of the reference is less frequent, because you're synthesizing literature, not rewriting a mashup of everything you found.