Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common equities	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock	Previously Reported Retained Earnings
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax				$ 0
Beginning Balance at Dec. 31, 2018		$ 397	$ 1,281	7,625	$ 22	$ (1,492)	$ 7,625
Share-based awards		0	(12)			19
Share-based compensation			23
Other			3			2
Net Income	$ 1,371			1,371
Dividends declared				(274)
Other comprehensive income	420				420
Shares acquired - share repurchase authorization						(5)
Shares acquired - share-based compensation plans						(9)
Ending Balance at Sep. 30, 2019	9,371	$ 397	1,295	8,722	442	(1,485)
Beginning Balance (in shares) at Dec. 31, 2018		162.8
Share-based awards (in shares)		0.6
Shares acquired - share repurchase authorization (in shares)		0.0
Ending Balance (in shares) at Sep. 30, 2019		163.4
Dividends declared per common share		$ 1.68
Increase to allowance through retained earnings for ASU 2016-13, after-tax				0
Beginning Balance at Jun. 30, 2019		$ 397	1,286	8,566	364	(1,482)	8,566
Share-based awards		0	1			3
Share-based compensation			7
Other			1			1
Net Income	248			248
Dividends declared				(92)
Other comprehensive income	78				78
Shares acquired - share repurchase authorization						(5)
Shares acquired - share-based compensation plans						(2)
Ending Balance at Sep. 30, 2019	9,371	$ 397	1,295	8,722	442	(1,485)
Beginning Balance (in shares) at Jun. 30, 2019		163.3
Share-based awards (in shares)		0.1
Shares acquired - share repurchase authorization (in shares)		0.0
Ending Balance (in shares) at Sep. 30, 2019		163.4
Dividends declared per common share		$ 0.56
Increase to allowance through retained earnings for ASU 2016-13, after-tax	(2)			(2)
Beginning Balance at Dec. 31, 2019	9,864	$ 397	1,306	9,255	448	(1,544)	9,257
Share-based awards		0	(16)			12
Share-based compensation			24
Other			4			3
Net Income	167			167
Dividends declared				(290)
Other comprehensive income	238				238
Shares acquired - share repurchase authorization						(256)
Shares acquired - share-based compensation plans						(3)
Ending Balance at Sep. 30, 2020	9,745	$ 397	1,318	9,132	686	(1,788)
Beginning Balance (in shares) at Dec. 31, 2019		162.9
Share-based awards (in shares)		0.4
Shares acquired - share repurchase authorization (in shares)		(2.5)
Ending Balance (in shares) at Sep. 30, 2020		160.8
Dividends declared per common share		$ 1.80
Increase to allowance through retained earnings for ASU 2016-13, after-tax				0
Beginning Balance at Jun. 30, 2020		$ 397	1,309	8,745	597	(1,790)	$ 8,745
Share-based awards		0	0			0
Share-based compensation			8
Other			1			2
Net Income	484			484
Dividends declared				(97)
Other comprehensive income	89				89
Shares acquired - share repurchase authorization						0
Shares acquired - share-based compensation plans						0
Ending Balance at Sep. 30, 2020	$ 9,745	$ 397	$ 1,318	$ 9,132	$ 686	$ (1,788)
Beginning Balance (in shares) at Jun. 30, 2020		160.8
Share-based awards (in shares)		0.0
Shares acquired - share repurchase authorization (in shares)		0.0
Ending Balance (in shares) at Sep. 30, 2020		160.8
Dividends declared per common share		$ 0.60