At first choose your API level from the following links:
API Level 17: http://dl-ssl.google.com/android/repository/docs-17_r02.zip
API Level 18: http://dl-ssl.google.com/android/repository/docs-18_r02.zip
API Level 19: http://dl-ssl.google.com/android/repository/docs-19_r02.zip
Android-L API doc: http://dl-ssl.google.com/android/repository/docs-L_r01.zip
API Level 24 doc: https://dl-ssl.google.com/android/repository/docs-24_r01.zip
download and extract it in your sdk driectory.
In your eclipse IDE:
at project -> properties -> java build path -> Libraries -> Android x.x -> android.jar -> javadoc
press edit in right:
javadoc URL -> Browse
select "docs/reference/" in archive extracted directory
press validate
... to validate this javadoc.
In your IntelliJ IDEA
at file -> Project Structure
Select SDKs from left panel -> select your sdk from middle panel -> in right panel go to Documentation Paths
tab so click plus icon and select docs/reference/
in archive extracted directory.
enjoy the offline javadoc...