Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	AOCI Attributable to Parent [Member]	Parent [Member]	Parent [Member] Cumulative Effect, Period of Adoption, Adjustment
Balance at period start at Dec. 31, 2018		$ 2	$ 3,878	$ (233)	$ (8)	$ (425)	$ 3,222	$ (8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend, preferred stock				(5)			(5)
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised			8				8
Net income (loss)	$ (1,337)			(1,337)		0	(1,337)
Other Comprehensive Income (Loss), Net of Tax	21			0		21	21
Comprehensive Income (Loss), Net	(1,316)			(1,337)		21	(1,316)
Balance at period end at Jun. 30, 2019		2	3,886	(1,583)		(404)	1,901
Balance at period start at Mar. 31, 2019		2	3,879	(551)		(403)	2,927
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend, preferred stock				(3)			(3)
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised			7				7
Net income (loss)	(1,029)			(1,029)			(1,029)
Other Comprehensive Income (Loss), Net of Tax	(1)					(1)	(1)
Comprehensive Income (Loss), Net	(1,030)			(1,029)		(1)	(1,030)
Balance at period end at Jun. 30, 2019		2	3,886	(1,583)		(404)	1,901
Balance at period start at Dec. 31, 2019	1,300	2	3,890	(2,185)		(407)	1,300
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend, preferred stock				(5)			(5)
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised			6				6
Net income (loss)	(100)			(100)			(100)
Other Comprehensive Income (Loss), Net of Tax	(26)					(26)	(26)
Comprehensive Income (Loss), Net	(126)			(100)		(26)	(126)
Balance at period end at Jun. 30, 2020	1,175	2	3,896	(2,290)		(433)	1,175
Balance at period start at Mar. 31, 2020		2	3,891	(2,236)		(437)	1,220
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend, preferred stock				(3)			(3)
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised			5				5
Net income (loss)	(51)			(51)			(51)
Other Comprehensive Income (Loss), Net of Tax	4					4	4
Comprehensive Income (Loss), Net	(47)			(51)		4	(47)
Balance at period end at Jun. 30, 2020	$ 1,175	$ 2	$ 3,896	$ (2,290)		$ (433)	$ 1,175