Stock-Based Compensation - Summary of Changes in Status of Time-Based Awards (Details) - Time-based Awards	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Units
Non-vested at beginning of period (in units) | shares	64,980
Granted (in units) | shares	23,000
Vested (in units) | shares	(20,900)
Forfeited (in units) | shares	(1,100)
Non-vested at end of period (in units) | shares	65,980
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 58.56
Granted (in dollars per share) | $ / shares	76.62
Vested (in dollars per share) | $ / shares	61.03
Forfeited (in dollars per share) | $ / shares	60.13
Non-vested at end of period (in dollars per share) | $ / shares	$ 64.04
CECONY
Units
Non-vested at beginning of period (in units) | shares	61,630
Granted (in units) | shares	21,800
Vested (in units) | shares	(19,800)
Forfeited (in units) | shares	(1,050)
Non-vested at end of period (in units) | shares	62,580
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 58.55
Granted (in dollars per share) | $ / shares	76.62
Vested (in dollars per share) | $ / shares	61.03
Forfeited (in dollars per share) | $ / shares	60.43
Non-vested at end of period (in dollars per share) | $ / shares	$ 64.03