Stock-Based Compensation - Summary of Changes in Status of Time-Based Awards (Details) - Time-based Awards	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Units
Non-vested at beginning of period (in shares) | shares	65,180
Granted (in shares) | shares	24,850
Vested (in shares) | shares	(20,980)
Forfeited (in shares) | shares	(1,800)
Non-vested at end of period (in shares) | shares	67,250
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 77.42
Granted (in dollars per share) | $ / shares	84.81
Vested (in dollars per share) | $ / shares	76.62
Forfeited (in dollars per share) | $ / shares	79.12
Non-vested at end of period (in dollars per share) | $ / shares	$ 80.36
CECONY
Units
Non-vested at beginning of period (in shares) | shares	61,380
Granted (in shares) | shares	23,350
Vested (in shares) | shares	(19,830)
Forfeited (in shares) | shares	(1,800)
Non-vested at end of period (in shares) | shares	63,100
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 77.42
Granted (in dollars per share) | $ / shares	84.81
Vested (in dollars per share) | $ / shares	76.62
Forfeited (in dollars per share) | $ / shares	79.12
Non-vested at end of period (in dollars per share) | $ / shares	$ 80.36