Accounting Policies (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Jan. 01, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Provision for income taxes		$ 117	$ 36
Other assets		3,085		$ 3,705
Deferred Tax Liabilities, Gross		524		504
Other liabilities and deferred income		2,084		2,280
Accumulated other comprehensive income		(579)		(478)
Retained Earnings (Accumulated Deficit)		10,663		10,818
Net income		845	(6)
Increase (Decrease) in Deferred Income Taxes		13	38
Net change in other liabilities		229	(758)
Cash distributions to parent		(1,000)	(343)
Increase (Decrease) in Other Operating Assets and Liabilities, Net		114	63
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		(15,311)	(15,450)	(15,567)	$ (16,389)
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income		$ 845	(6)
Accounting Standards Update 2019-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Provision for income taxes	$ 27
Other assets	(888)
Deferred Tax Liabilities, Gross	(2,403)
Other liabilities and deferred income	(26)
Accumulated other comprehensive income	(65)
Retained Earnings (Accumulated Deficit)	1,606
Net income	(27)
Increase (Decrease) in Deferred Income Taxes	310
Net change in other liabilities	(175)
Cash distributions to parent	(68)
Increase (Decrease) in Other Operating Assets and Liabilities, Net	40
Accounting Standards Update 2019-12 | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			40
Accounting Standards Update 2016-13 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			202
Accounting Standards Update 2019-12, 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			242
Accounting Standards Update 2019-12, 2016-13 | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			242
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Provision for income taxes			9
Other assets				4,593
Deferred Tax Liabilities, Gross	3,400			2,907
Other liabilities and deferred income				2,306
Accumulated other comprehensive income				(413)
Retained Earnings (Accumulated Deficit)				$ 9,212
Net income			21
Increase (Decrease) in Deferred Income Taxes			(272)
Net change in other liabilities			(583)
Cash distributions to parent			(275)
Deferred Tax Liabilities, Leasing Arrangements	2,800
Deferred Tax Assets, Gross	$ 1,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	9.70%			26.20%
Increase (Decrease) in Other Operating Assets and Liabilities, Net			$ (103)
Previously Reported | Foreign Tax Authority
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Tax Assets, Gross	$ 700