Stock-Based Compensation - Summary of Changes in Status of Time-Based Awards (Details) - Time-based Awards	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Units
Non-vested at beginning of period (in shares) | shares	67,250
Granted (in shares) | shares	22,450
Vested (in shares) | shares	(20,750)
Forfeited (in shares) | shares	(1,512)
Non-vested at end of period (in shares) | shares	67,438
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 80.36
Granted (in dollars per share) | $ / shares	78.00
Vested (in dollars per share) | $ / shares	77.66
Forfeited (in dollars per share) | $ / shares	80.30
Non-vested at end of period (in dollars per share) | $ / shares	$ 80.40
CECONY
Units
Non-vested at beginning of period (in shares) | shares	63,100
Granted (in shares) | shares	20,900
Vested (in shares) | shares	(19,650)
Forfeited (in shares) | shares	(1,512)
Non-vested at end of period (in shares) | shares	62,838
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 80.36
Granted (in dollars per share) | $ / shares	78.00
Vested (in dollars per share) | $ / shares	77.66
Forfeited (in dollars per share) | $ / shares	80.30
Non-vested at end of period (in dollars per share) | $ / shares	$ 80.42