The FRED series Debt Outstanding Domestic Nonfinancial Sectors - Federal Government Sector is now known as Federal Government; Credit Market Instruments; Liability.
The source series id is LA314104005.Q.
This series appears in Table D.3. For further information see the assistance provided in the guide to the Financial Accounts at http://www.federalreserve.gov/apps/fof/.
Board of Governors of the Federal Reserve System (US), Federal Government; Credit Market Instruments; Liability, Level [FGSDODNS], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/FGSDODNS, March 18, 2018.