As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOSS OF LEFT AC BUS AND ALL CAPTAIN'S INSTRUMENTS OCCURRED AFTER TAKEOFF. CREW RESET LEFT AC BUS, CIRCUIT BREAKER AND INSTRUMENTS WERE REGAINED. CREW DECLARED AN EMERGENCY. RETURNED TO DTW AND AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED LEFT AC BUS, CIRCUIT BREAKER AND OPERATIONAL CHECK NORMAL.