How to restore postgres db from gzip file using psql? (arelle: XBRL SEC DB)

You should run psql as postgres user, not zcat, so try to use following:

zcat xbrldb_SEC_pg_2014-11-02.pg.gzip | sudo -u postgres psql public

PS pg_restore is an utility, not a PostgreSQL command, that means you should run it from command line, not from psql.

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