Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) facility	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
ROU assets, operating leases	$ 499	$ 133
Lease liabilities, operating leases	498	141
ROU assets, finance leases	62	68
Lease liabilities, finance leases	$ 56	$ 63
Weighted average incremental borrowing rate at the lease inception, operating leases	3.73%	4.31%
Weighted average incremental borrowing rate at the lease inception, finance leases	3.15%	2.72%
Weighted-average remaining lease term, operating leases	31 years	19 years
Weighted-average remaining lease term, finance leases	14 years	10 years
Expected lease payments over the remaining terms of the leases	$ 981
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	450
Operating Lease, Expense	91
Net investment in sales-type leases	50	$ 69
Losses at commencement of sales-type leases		$ (20)
Expected lease payments over the remaining terms of the power sales agreements	$ 150
Number of facilities | facility	1
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lease extension term, operating lease	27 years
Lessee extension term, finance lease	27 years