You asked about whether the following sentence is correc:"For the detail, please have a look at the attached."
Your sentence is ALMOST correct, and just needs one correction, as follows:
"For the DETAILS, please have a look at the attached."
We normally use this word in the plural instead of just the singular, especially when referring to a file or document which contains detailed information, because usually there's more than just one small detail.
Please have a look at the definitions and examples below for "detail" and "details" from the Cambridge Dictionaries Online
(
dictionary.cambridge.org/define.asp?key=21210&dict=CALD):
detail (INFORMATION)noun
1[C] a single piece of information or fact about something:
-She insisted on telling me every single detail of what they did to her in hospital.
-We don't know the full/precise details of the story yet.
-She refused to disclose/divulge any details about of the plan.
details plural noun
information about someone or something:
Can I have your details (=name and address, etc. )Please?
I've sent off for the details of a job I saw advertised in the paper.
A police officer took down the details of what happened.
