Consolidated Statement of Shareholder's Interest - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Shareholder's Interest [Roll Forward]
Net income	$ 845	$ (6)
Other Comprehensive Income (Loss), Net of Tax	(101)	(348)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance	15,567	16,389
Distributions declared	1,000	343
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	15,311	15,450
Accounting Standards Update 2019-12, 2016-13
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		(242)
Shareholder's Interest [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	5,227	5,227
Net income	0	0
Other Comprehensive Income (Loss), Net of Tax	0	0
Distributions declared	0	0
Balance at end of period	5,227	5,227
Shareholder's Interest [Member] | Accounting Standards Update 2019-12, 2016-13
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		0
Accumulated Other Comprehensive Income/(Loss) (Note11) [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	(478)	(850)
Net income	0	0
Other Comprehensive Income (Loss), Net of Tax	(101)	(348)
Distributions declared	0	0
Balance at end of period	(579)	(1,198)
Accumulated Other Comprehensive Income/(Loss) (Note11) [Member] | Accounting Standards Update 2019-12, 2016-13
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		0
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	10,818	12,012
Net income	845	(6)
Other Comprehensive Income (Loss), Net of Tax	0	0
Distributions declared	1,000	343
Balance at end of period	$ 10,663	11,421
Retained Earnings [Member] | Accounting Standards Update 2016-13 [Member]
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		(202)
Retained Earnings [Member] | Accounting Standards Update 2019-12
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		(40)
Retained Earnings [Member] | Accounting Standards Update 2019-12, 2016-13
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		$ (242)