Consolidated Statements Of Changes In Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-Controlling Interest [Member]
Balance at Dec. 31, 2018	$ 2,937,149	$ 144,784	$ 559,432	$ 2,084,824	$ 241,163	$ (34,236)	$ (64,669)	$ 5,851
Net income	97,055				97,138			(83)
Other comprehensive income (loss)	76,650						76,650
Distributions to non-controlling interest	(310)							(310)
Purchase of treasury stock	(39,699)					(39,699)
Issuance of stock, under purchase and equity compensation plans	(4)			(13,392)		13,388
Stock-based compensation	3,480			3,480
Cash dividends per share, Common Stock, Cash	(28,858)				(28,858)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Mar. 31, 2019	3,043,213	144,784	559,432	2,074,912	307,193	(60,547)	11,981	5,458
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-13	3,766				3,766
Balance at Dec. 31, 2019	3,138,472	144,784	563,978	2,151,464	201,562	(37,548)	110,444	3,788
Net income	49,603				51,857			(2,254)
Other comprehensive income (loss)	142,692						142,692
Distributions to non-controlling interest	(85)							(85)
Purchase of treasury stock	(53,145)					(53,145)
Issuance of stock, under purchase and equity compensation plans	(26)			(21,570)		21,544
Stock-based compensation	3,729			3,729
Cash dividends per share, Common Stock, Cash	(30,292)				(30,292)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Mar. 31, 2020	$ 3,252,464	$ 144,784	$ 563,978	$ 2,133,623	$ 224,643	$ (69,149)	$ 253,136	$ 1,449