Inventory (Tables)

12 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventory consisted of:

	As of December 31,
	2016		2015
	(In millions)
Fuel oil	$	289	$	312
Coal/Lignite	334		471
Natural gas	28		12
Spare parts	413		437
Other	47		20
Total Inventory	$	1,111	$	1,252