Consolidated Statement of Shareholder's Interest - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Shareholder's Interest [Roll Forward]
Net income	$ 859	$ 407	$ 21	$ 571	$ 613	$ 603	$ 1,287	$ 1,787
Other Comprehensive Income (Loss), Net of Tax	238	87	(348)	(210)	8	20
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	14,284	13,762	13,543	14,155	14,894	14,923	14,284	14,155
Distributions declared	575	275	275	1,100	650	675
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	14,284	13,762	13,543	14,155	14,894	14,923	14,284	14,155
Accounting Standards Update 2016-13 [Member]
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(202)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(202)
Shareholder's Interest [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	5,227	5,227	5,227	5,227	5,227	5,227	5,227	5,227
Net income	0	0	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0	0	0
Distributions declared	0	0	0	0	0	0
Balance at end of period	5,227	5,227	5,227	5,227	5,227	5,227	5,227	5,227
Shareholder's Interest [Member] | Accounting Standards Update 2016-13 [Member]
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			0
Accumulated Other Comprehensive Income/(Loss) (Note11) [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	(1,046)	(1,133)	(785)	(801)	(809)	(829)	(785)	(829)
Net income	0	0	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	238	87	(348)	(210)	8	20
Distributions declared	0	0	0	0	0	0
Balance at end of period	(808)	(1,046)	(1,133)	(1,011)	(801)	(809)	(808)	(1,011)
Accumulated Other Comprehensive Income/(Loss) (Note11) [Member] | Accounting Standards Update 2016-13 [Member]
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			0
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	9,581	9,449	9,905	10,468	10,505	10,577	9,905	10,577
Net income	859	407	21	571	613	603
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0	0	0
Distributions declared	575	275	275	1,100	650	675
Balance at end of period	$ 9,865	$ 9,581	9,449	$ 9,939	$ 10,468	$ 10,505	$ 9,865	$ 9,939
Retained Earnings [Member] | Accounting Standards Update 2016-13 [Member]
Shareholder's Interest [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(202)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ (202)