Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Millions		Total		Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock and Other		AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding					471,000
Total shareholders' equity at Dec. 31, 2017		$ 25,154		$ 2,475	$ 550	$ 9,000	$ 17,540	$ (3,591)	[1]	$ (820)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	[2]	(10)					144			(154)
Net Income (Loss) Attributable to Parent		643					643
Other Comprehensive Income (Loss), Net of Tax		(548)								(548)
Noncontrolling Interest, Period Increase (Decrease)		(2)						(2)	[1]
Dividends, Common Stock, Cash		(187)					(187)
Dividends, Preferred Stock, Cash	[3]	(31)					(31)
Stock Redeemed or Called During Period, Value		(450)		(450)
Treasury Stock, Shares, Acquired					(5,000)
Treasury Stock, Value, Acquired, Cost Method		(330)						(330)	[1]
Stock Issued During Period, Value, Stock Options Exercised		32				0		32	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period					1,000
Stock Issued During Period, Shares, Other					2,000
Stock Issued During Period, Value, Other		2			$ 2
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures					1,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		(4)				(40)	(2)	38	[1]
Total shareholders' equity at Mar. 31, 2018		24,269		2,025	$ 552	8,960	18,107	(3,853)	[1]	(1,522)
Total shareholders' equity at Dec. 31, 2017		25,154		2,475	550	9,000	17,540	(3,591)	[1]	(820)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	[4]									(154)
Net Income (Loss) Attributable to Parent		1,365
Dividends, Preferred Stock, Cash		(55)
Total shareholders' equity at Jun. 30, 2018		24,316		2,025	$ 552	8,980	18,616	(4,178)	[1]	(1,679)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding					470,000
Total shareholders' equity at Mar. 31, 2018		24,269		2,025	$ 552	8,960	18,107	(3,853)	[1]	(1,522)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent		722					722
Other Comprehensive Income (Loss), Net of Tax		(157)								(157)
Noncontrolling Interest, Period Increase (Decrease)		2						2	[1]
Dividends, Common Stock, Cash		(187)					(187)
Dividends, Preferred Stock, Cash	[3]	(25)					(25)
Treasury Stock, Shares, Acquired					(5,000)
Treasury Stock, Value, Acquired, Cost Method		(330)						(330)	[1]
Stock Issued During Period, Value, Stock Options Exercised		0				(1)		1	[1]
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		22				21	(1)	2	[1]
Total shareholders' equity at Jun. 30, 2018		$ 24,316		2,025	$ 552	8,980	18,616	(4,178)	[1]	(1,679)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding					465,000
Common Stock, Shares, Outstanding		446,888	[5]		447,000
Total shareholders' equity at Dec. 31, 2018		$ 24,280		2,025	$ 553	9,022	19,522	(5,422)	[6]	(1,420)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	[7]	31					31
Net Income (Loss) Attributable to Parent		580					580
Other Comprehensive Income (Loss), Net of Tax		454								454
Noncontrolling Interest, Period Increase (Decrease)		(2)						(2)	[6]
Dividends, Common Stock, Cash		(222)					(222)
Dividends, Preferred Stock, Cash	[8]	(26)					(26)
Treasury Stock, Shares, Acquired					(4,000)
Treasury Stock, Value, Acquired, Cost Method		(250)						(250)	[6]
Stock Issued During Period, Value, Stock Options Exercised		2				(1)		3	[6]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures					1,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		(24)				(83)	(3)	62	[6]
Total shareholders' equity at Mar. 31, 2019		24,823		2,025	$ 553	8,938	19,882	(5,609)	[6]	(966)
Total shareholders' equity at Dec. 31, 2018		24,280		2,025	553	9,022	19,522	(5,422)	[6]	(1,420)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent		1,268
Dividends, Preferred Stock, Cash		(51)
Total shareholders' equity at Jun. 30, 2019		25,862		2,025	$ 553	8,965	20,319	(5,599)	[6]	(401)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding					444,000
Total shareholders' equity at Mar. 31, 2019		24,823		2,025	$ 553	8,938	19,882	(5,609)	[6]	(966)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent		688					688
Other Comprehensive Income (Loss), Net of Tax		565								565
Noncontrolling Interest, Period Increase (Decrease)		2						2	[6]
Dividends, Common Stock, Cash		(222)					(222)
Dividends, Preferred Stock, Cash	[8]	(25)					(25)
Stock Issued During Period, Value, Stock Options Exercised		3				(3)		6	[6]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures					0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		28				30	(4)	2	[6]
Total shareholders' equity at Jun. 30, 2019		$ 25,862		$ 2,025	$ 553	$ 8,965	$ 20,319	$ (5,599)	[6]	$ (401)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		443,858	[5]		444,000

[1] At June 30, 2018, includes ($4,281) million for treasury stock, and $103 million for noncontrolling interest. At March 31, 2018, includes ($3,953) million for treasury stock, less than ($1) million for the compensation element of restricted stock, and $101 million for noncontrolling interest.

[2] Related to the Company’s adoption of ASU 2014-09, ASU 2016-01, ASU 2017-12, and ASU 2018-02 on January 1, 2018. See Note 1, “Significant Accounting Policies,” to the Company's 2018 Annual Report on Form 10-K for additional information.

[3] For the three months ended June 30, 2018, dividends were $1,022.22 per share for both Series A and B Preferred Stock, $1,406.25 per share for Series F Preferred Stock, $1,262.50 per share for Series G Preferred Stock, and $1,722.57 per share for Series H Preferred Stock. For the three months ended March 31, 2018, dividends were $1,000.00 per share for both Series A and B Preferred Stock, $1,468.75 per share for Series E Preferred Stock, $1,406.25 per share for Series F Preferred Stock, $1,262.50 per share for Series G Preferred Stock, and $1,281.25 per share for Series H Preferred Stock.

[4] Related to the Company’s early adoption of ASU 2018-02 on January 1, 2018. See Note 1, “Significant Accounting Policies,” to the Company's 2018 Annual Report on Form 10-K for additional information.

[5] Includes restricted shares of 4 thousand and 7 thousand at June 30, 2019 and December 31, 2018, respectively.

[6] At June 30, 2019, includes ($5,702) million for treasury stock and $103 million for noncontrolling interest. At March 31, 2019, includes ($5,710) million for treasury stock and $101 million for noncontrolling interest.

[7] Related to the Company’s adoption of ASU 2016-02 on January 1, 2019. See Note 1, “Significant Accounting Policies,” for additional information.

[8] For the three months ended June 30, 2019, dividends were $1,022.22 per share for both Series A and B Preferred Stock, $1,406.25 per share for Series F Preferred Stock, $1,262.50 per share for Series G Preferred Stock, and $1,281.25 per share for Series H Preferred Stock. For the three months ended March 31, 2019, dividends were $1,000.00 per share for both Series A and B Preferred Stock, $1,406.25 per share for Series F Preferred Stock, $1,262.50 per share for Series G Preferred Stock, and $1,281.25 per share for Series H Preferred Stock.