Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands		Total	Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series A Warrants [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]	Treasury Stock [Member] Series A Warrants [Member]
Beginning balance at Dec. 31, 2017		$ 16,250,819	$ 1,231,500	$ 79,909	$ 1,847	$ 6,590,855		$ 10,164,804	$ (363,814)	$ (1,454,282)
Cumulative effect of change in accounting principle — equity securities		(16,853)						16,853	(16,853)
Total comprehensive income		250,034						352,610	(102,576)
Preferred stock cash dividends	[1]	(18,130)						(18,130)
Exercise of stock warrants into common stock							$ (3,455)				$ 3,455
Purchases of treasury stock		(720,966)								(720,966)
Stock-based compensation plans:
Compensation expense, net		5,833		(25)		(15,362)				21,220
Exercises of stock options, net		42,100				(1,945)				44,045
Stock purchase plan		11,124				2,358				8,766
Directors’ stock plan		589				74				515
Deferred compensation plans, net, including dividend equivalents		(48)			(172)	(244)		(18)		386
Common stock cash dividends		(111,661)						(111,661)
Ending balance at Mar. 31, 2018		15,709,694	1,231,500	79,884	1,675	6,572,281		10,404,458	(483,243)	(2,096,861)
Beginning balance at Dec. 31, 2018		15,460,191	1,231,500	79,883	1,726	6,579,342		11,516,672	(420,081)	(3,528,851)
Total comprehensive income		614,814						482,742	132,072
Preferred stock cash dividends	[1]	(18,130)						(18,130)
Purchases of treasury stock		(365,628)								(365,628)
Stock-based compensation plans:
Compensation expense, net		18,120		(12)		(7,606)				25,738
Exercises of stock options, net		4,727				(2,818)				7,545
Stock purchase plan		11,832				(67)				11,899
Directors’ stock plan		529				(84)				613
Deferred compensation plans, net, including dividend equivalents		(64)			(212)	(316)		(22)		486
Performance share unit dividends						29		(29)
Common stock cash dividends		(138,862)						(138,862)
Ending balance at Mar. 31, 2019		$ 15,587,529	$ 1,231,500	$ 79,871	$ 1,514	$ 6,568,480		$ 11,842,371	$ (288,009)	$ (3,848,198)

[1] For each of the three-month periods ended March 31, 2019 and 2018, dividends per preferred share were: Preferred Series A- $15.9375; Preferred Series C - $15.9375; Preferred Series E - $16.125; and Preferred Series F - $128.125. See accompanying notes to financial statements.