Acquisitions Acquisitions (Narrative) (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 31, 2016 USD ($) MW	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Payments to Acquire Property, Plant, and Equipment		$ (949,329)	$ 0
Union Power Station [Member]
Capacity Per Power Block | MW	495
Payments to Acquire Property, Plant, and Equipment	$ (949,000)
Capacity Of Power Plant Unit | MW	1,980
Entergy Arkansas [Member]
Payments to Acquire Property, Plant, and Equipment	$ (237,000)	(237,324)	0
Entergy Arkansas [Member] | Union Power Station [Member]
Percentage of Undivided Ownership Interest	25.00%
Payments to Acquire Property, Plant, and Equipment	$ (237,324)
Power Blocks Purchased	1
Entergy Louisiana [Member]
Payments to Acquire Property, Plant, and Equipment	$ (474,000)	(474,670)	0
Entergy Louisiana [Member] | Union Power Station [Member]
Percentage of Undivided Ownership Interest	50.00%
Payments to Acquire Property, Plant, and Equipment	$ (474,670)
Power Blocks Purchased	2
Entergy New Orleans [Member]
Payments to Acquire Property, Plant, and Equipment	$ (237,000)	$ (237,335)	$ 0
Entergy New Orleans [Member] | Union Power Station [Member]
Percentage of Undivided Ownership Interest	25.00%
Payments to Acquire Property, Plant, and Equipment	$ (237,335)
Power Blocks Purchased	1