Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 71	$ 66
Restricted cash	5	23
Accounts receivable	1,789	1,758
Property, plant, and equipment, net	21,650	20,721
Goodwill	2,293	2,293	$ 2,286
Intangible assets	828	842
Total Assets	36,288	33,767	$ 32,041
LIABILITIES
Current portion long-term debt, including capital leases	1,499	109
Mortgage bonds, notes, and other	10,982	11,039
Variable interest entity, primary beneficiary, restricted
ASSETS
Cash and cash equivalents	39	37
Restricted cash	5	8
Accounts receivable	46	53
Inventories	93	117
Property, plant, and equipment, net	441	475
Goodwill	25	25
Intangible assets	557	572
Other current and long-term assets	3	4
Total Assets	1,209	1,291
LIABILITIES
Accounts payable and accrued current liabilities	34	73
Current portion long-term debt, including capital leases	0	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	19	17
Total liabilities	53	95
SGG
ASSETS
Cash and cash equivalents	25	23
Restricted cash	0	0
Accounts receivable	9	11
Inventories	1	3
Property, plant, and equipment, net	395	400
Goodwill	25	25
Intangible assets	557	572
Other current and long-term assets	3	4
Total Assets	1,015	1,038
LIABILITIES
Accounts payable and accrued current liabilities	3	26
Current portion long-term debt, including capital leases	0	0
Mortgage bonds, notes, and other	0	0
Other current and long-term liabilities	9	1
Total liabilities	$ 12	27
VIE percentage	100.00%
VIE ownership percentage	55.00%
Other
ASSETS
Cash and cash equivalents	$ 14	14
Restricted cash	5	8
Accounts receivable	37	42
Inventories	92	114
Property, plant, and equipment, net	46	75
Goodwill	0	0
Intangible assets	0	0
Other current and long-term assets	0	0
Total Assets	194	253
LIABILITIES
Accounts payable and accrued current liabilities	31	47
Current portion long-term debt, including capital leases	0	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	10	16
Total liabilities	$ 41	$ 68