Stock-Based Compensation - Summary of Status of Stock Options (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Shares
Outstanding at beginning of period (in shares) | shares	79,125
Exercised (in shares) | shares	79,125
Forfeited (in shares) | shares	0
Outstanding at end of period (in shares) | shares	0
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 43.50
Exercised (in dollars per share) | $ / shares	43.50
Forfeited (in dollars per share) | $ / shares	0.00
Outstanding at end of period (in dollars per share) | $ / shares	$ 0.00
CECONY
Shares
Outstanding at beginning of period (in shares) | shares	65,775
Exercised (in shares) | shares	65,775
Forfeited (in shares) | shares	0
Outstanding at end of period (in shares) | shares	0
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 43.50
Exercised (in dollars per share) | $ / shares	43.50
Forfeited (in dollars per share) | $ / shares	0.00
Outstanding at end of period (in dollars per share) | $ / shares	$ 0.00