Reading for gist (the main idea) and the information :
The general ideais the topic of the text which is discussed generally for the whole paragraph.
The topic sentence of a paragraph contains the main idea.
The main idea can be the first sentences of a paragraph or in the last sentence of a paragraph, or somewhere in the middle of paragraph or stated implicitly.
The specific information is the information which is stated explicitly in the text.
The detailed information is the information which is given in detail to support the main idea in the text.