Leases (Policies)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Early Termination [Policy Text Block]	The option to extend or terminate a lease is based on customary early termination provisions in the contract, such as payment defaults, bankruptcy, and lack of performance on energy delivery.
Separation of Lease and Nonlease Components [Policy Text Block]	Capacity payments are generally considered lease elements as they cover the majority of available output from a facility. The allocation of contract payments between the lease and non-lease elements is made at the inception of the lease.
Incremental Borrowing Rate [Policy Text Block]	As our leases do not provide an implicit rate, we use the subsidiaries’ incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments.
Short-term Leases [Policy Text Block]	Leases with an initial term of 12 months or less are not recorded on the balance sheet, but are expensed on a straight-line basis over the lease term.