Pivot With Header And Details

I need to display data from both header and detail, details has to come from other table also

CREATE TABLE [dbo].[Table_Detail](
[Header_ID] [int] NOT NULL,
[Name] [nvarchar](50) NOT NULL,
[DescValue] [nvarchar](max) NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

[code]....

..consider the dept code, where the values are now comming from table and need result if the data is not displayed from table and they are static..

use case when 'Bo' then 'Branch Office'
when 'Ro' then 'Reginal Office'
when 'So' then 'Sub Division Office'
when 'Ho' then 'Head Office'

How to replace my above query

Below is my sql

SELECT *
FROM
(
SELECT h.Header_ID,
td.ListNumber,
td.PhaseCode,

[code]...