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, 2019	$ 1,536	$ 1,203	$ 42	$ 0	$ 0	$ 232	$ 0	$ 60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(405)
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(405)	(315)	(90)	0	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(90)
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	65
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	100
Beginning balance at Dec. 31, 2020	1,140	759	79	0	0	242	(1)	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(3)
Stock-based compensation	6	0	0	0	0	6	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(6)	(2)	0	0	0	0	(4)	0
Ending balance at Jun. 30, 2021	1,123	732	87	0	0	249	(5)	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(3)	(12)	8	0	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	8
Noncontrolling Interest, Change in Redemption Value	(14)	(14)
Beginning balance at Mar. 31, 2021	1,123	761	61	0	0	246	(5)	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(2)
Stock-based compensation	2	0	0	0	0	2	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	0	0	0	0	0	0	0	0
Ending balance at Jun. 30, 2021	1,123	732	87	0	0	249	(5)	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(2)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	27	(29)	$ 27	$ 0	$ 0	$ 0	$ 0	$ 0
Noncontrolling Interest, Change in Redemption Value	(1)	$ (1)
Public Finance Puerto Rico Net Par Outstanding	$ 1,067