Consolidated Statements Of Equity (Deficit) - USD ($) $ in Millions	Successor [Member] Common Stock [Member]	Successor [Member] Additional Paid-In Capital [Member]	Successor [Member] Retained Earnings (Deficit)/Accumulated Deficit [Member]	Successor [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Successor [Member] Treasury Common Stock [Member]	Successor [Member]	Predecessor [Member] Common Stock [Member]	Predecessor [Member] Additional Paid-In Capital [Member]	Predecessor [Member] Retained Earnings (Deficit)/Accumulated Deficit [Member]	Predecessor [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Predecessor [Member] Treasury Common Stock [Member]	Predecessor [Member]
Balance at beginning at Dec. 31, 2019							$ 27	$ 4,815	$ (8,573)	$ (650)	$ (13)	$ (4,394)
Balance (in shares) at Dec. 31, 2019							106,025,000				(894,000)
Stock plans								1				1
Stock plans (in shares)											(143,000)
Net income (loss)									(186)			(186)
Other comprehensive income (loss), net of tax										86		86
Balance at ending at Mar. 31, 2020							$ 27	4,816	(8,759)	(564)	$ (13)	(4,493)
Balance (in shares) at Mar. 31, 2020							106,025,000				(1,037,000)
Balance at beginning at Dec. 31, 2019							$ 27	4,815	(8,573)	(650)	$ (13)	(4,394)
Balance (in shares) at Dec. 31, 2019							106,025,000				(894,000)
Net income (loss)												(352)
Other comprehensive income (loss), net of tax												(182)
Balance at ending at Sep. 30, 2020							$ 27	4,818	(8,925)	(832)	$ (14)	(4,926)
Balance (in shares) at Sep. 30, 2020							106,025,000				(1,232,000)
Balance at beginning at Mar. 31, 2020							$ 27	4,816	(8,759)	(564)	$ (13)	(4,493)
Balance (in shares) at Mar. 31, 2020							106,025,000				(1,037,000)
Stock plans
Stock plans (in shares)											(77,000)
Net income (loss)									(181)			(181)
Other comprehensive income (loss), net of tax										(423)		(423)
Balance at ending at Jun. 30, 2020							$ 27	4,816	(8,940)	(987)	$ (13)	(5,097)
Balance (in shares) at Jun. 30, 2020							106,025,000				(1,114,000)
Stock plans								2			$ (1)	1
Stock plans (in shares)											(118,000)
Net income (loss)									15			15
Other comprehensive income (loss), net of tax										155		155
Balance at ending at Sep. 30, 2020							$ 27	4,818	(8,925)	(832)	$ (14)	(4,926)
Balance (in shares) at Sep. 30, 2020							106,025,000				(1,232,000)
Balance at beginning at Dec. 31, 2020							$ 27	4,817	(8,975)	(755)	$ (14)	(4,900)
Balance (in shares) at Dec. 31, 2020							106,025,000				(1,232,000)
Stock plans											$ (1)	(1)
Stock plans (in shares)											(122,000)
Net income (loss)									60			60
Other comprehensive income (loss), net of tax										11		11
Balance at ending at Mar. 31, 2021							$ 27	4,817	(8,915)	(744)	$ (15)	(4,830)
Balance (in shares) at Mar. 31, 2021							106,025,000				(1,354,000)
Balance at beginning at Dec. 31, 2020							$ 27	4,817	(8,975)	(755)	$ (14)	(4,900)
Balance (in shares) at Dec. 31, 2020							106,025,000				(1,232,000)
Net income (loss)												4,541
Other comprehensive income (loss), net of tax												359
Issuance of Successor common stock (in shares)						244,401,000
Balance at ending at Apr. 30, 2021	$ 2	$ 4,106				$ 4,108	$ 2	4,106				4,108
Balance (in shares) at Apr. 30, 2021	244,401,000						244,401,000
Balance at beginning at Mar. 31, 2021							$ 27	4,817	(8,915)	(744)	$ (15)	(4,830)
Balance (in shares) at Mar. 31, 2021							106,025,000				(1,354,000)
Stock plans								1				1
Net income (loss)									4,481			4,481
Other comprehensive income (loss), net of tax										348		348
Cancellation of Predecessor equity							$ (27)	(4,818)	4,434	396	$ 15
Cancellation of Predecessor equity (in shares)							(106,025,000)				1,354,000
Issuance of Successor common stock							$ 2	4,106				4,108
Issuance of Successor common stock (in shares)							244,401,000
Balance at ending at Apr. 30, 2021	$ 2	4,106				4,108	$ 2	4,106				4,108
Balance (in shares) at Apr. 30, 2021	244,401,000						244,401,000
Stock plans
Net income (loss)			99			99
Other comprehensive income (loss), net of tax				41		41
Balance at ending at Jun. 30, 2021	$ 2	4,106	99	41		4,248
Balance (in shares) at Jun. 30, 2021	244,401,000
Balance at beginning at Apr. 30, 2021	$ 2	4,106				4,108	$ 2	$ 4,106				$ 4,108
Balance (in shares) at Apr. 30, 2021	244,401,000						244,401,000
Net income (loss)						225
Other comprehensive income (loss), net of tax						$ 44
Issuance of Successor common stock (in shares)						244,401,000
Balance at ending at Sep. 30, 2021	$ 2	4,114	225	44		$ 4,385
Balance (in shares) at Sep. 30, 2021	244,407,000
Balance at beginning at Jun. 30, 2021	$ 2	4,106	99	41		4,248
Balance (in shares) at Jun. 30, 2021	244,401,000
Stock plans		8				8
Stock plans (in shares)	6,000
Net income (loss)			126			126
Other comprehensive income (loss), net of tax				3		3
Balance at ending at Sep. 30, 2021	$ 2	$ 4,114	$ 225	$ 44		$ 4,385
Balance (in shares) at Sep. 30, 2021	244,407,000