Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2018	$ 1,633	$ 1,421	$ (49)	$ 0	$ 0	$ 219	$ 0	$ 41
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(104)	(172)	68	0	0	0	0	0
Stock-based compensation	7	0	0	0	0	7	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(3)	(3)	0	0	0	0	0	0
Stock Issued During Period, Value, New Issues	0	0	0	0	0	0	0	0
Ending balance at Jun. 30, 2019	1,553	1,247	19	0	0	227	0	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
AMPS Impact on Stockholders Equity	19	0	0	0	0	0	0	19
Beginning balance at Mar. 31, 2019	1,666	1,376	23	0	0	224	(1)	44
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(132)	(128)	(3)	0	0	0	0	0
Stock-based compensation	3	0	0	0	0	3	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	0	(1)	0	0	0	0	0	0
Ending balance at Jun. 30, 2019	1,553	1,247	19	0	0	227	0	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
AMPS Impact on Stockholders Equity	16	0	0	0	0	0	0	16
Beginning balance at Dec. 31, 2019	1,536	1,203	42	0	0	232	0	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(405)	(315)	(90)	0	0	0	0	0
Stock-based compensation	6	0	0	0	0	6	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(3)	(2)	0	0	0	0	(1)	0
Ending balance at Jun. 30, 2020	1,129	881	(48)	0	0	237	(1)	60
Beginning balance at Mar. 31, 2020	1,062	917	(149)	0	0	235	(2)	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	65	(35)	100	0	0	0	0	0
Stock-based compensation	3	0	0	0	0	3	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	0	(1)	0	0	0	0	1	0
Ending balance at Jun. 30, 2020	$ 1,129	$ 881	$ (48)	$ 0	$ 0	$ 237	$ (1)	$ 60

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Value, after forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

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