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]
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02 [Member]	$ 0				$ (2,932)		$ 2,932
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-01 [Member]	0				33,320		(33,320)
Balance at Dec. 31, 2017	2,718,184	$ 144,784	$ 535,407	$ 1,815,360	221,374	$ (14,473)	14,108	$ 1,624
Net income	213,385				211,314			2,071
Other comprehensive income (loss)	(92,501)						(92,501)
Distributions to non-controlling interest	(299)							(299)
Purchase of treasury stock	(19,069)					(19,069)
Issuance of stock under purchase and equity compensation plans	(9)			(17,697)		17,688
Stock-based compensation	6,394			6,394
Cash dividends per share, Common Stock, Cash	(50,202)				(50,202)
Dividends per share, Preferred Stock, Cash	(4,500)				(4,500)
Balance at Jun. 30, 2018	2,771,383	144,784	535,407	1,804,057	408,374	(15,854)	(108,781)	3,396
Balance at Mar. 31, 2018	2,705,728	144,784	535,407	1,802,785	325,390	(15,681)	(89,563)	2,606
Net income	111,324				110,330			994
Other comprehensive income (loss)	(19,218)						(19,218)
Distributions to non-controlling interest	(204)							(204)
Purchase of treasury stock	(2,002)					(2,002)
Issuance of stock under purchase and equity compensation plans	(3)			(1,832)		1,829
Stock-based compensation	3,104			3,104
Cash dividends per share, Common Stock, Cash	(25,096)				(25,096)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Jun. 30, 2018	2,771,383	144,784	535,407	1,804,057	408,374	(15,854)	(108,781)	3,396
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	205,354				205,109			245
Other comprehensive income (loss)	173,567						173,567
Distributions to non-controlling interest	(3,464)							(3,464)
Purchase of treasury stock	(86,079)					(86,079)
Issuance of stock under purchase and equity compensation plans	(3)			(14,212)		14,209
Stock-based compensation	6,879			6,879
Cash dividends per share, Common Stock, Cash	(57,540)				(57,540)
Dividends per share, Preferred Stock, Cash	(4,500)				(4,500)
Balance at Jun. 30, 2019	3,171,363	144,784	559,432	2,077,491	384,232	(106,106)	108,898	2,632
Balance at Mar. 31, 2019	3,043,213	144,784	559,432	2,074,912	307,193	(60,547)	11,981	5,458
Net income	108,299				107,971			328
Other comprehensive income (loss)	96,917						96,917
Distributions to non-controlling interest	(3,154)							(3,154)
Purchase of treasury stock	(46,380)					(46,380)
Issuance of stock under purchase and equity compensation plans	1			(820)		821
Stock-based compensation	3,399			3,399
Cash dividends per share, Common Stock, Cash	(28,682)				(28,682)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Jun. 30, 2019	$ 3,171,363	$ 144,784	$ 559,432	$ 2,077,491	$ 384,232	$ (106,106)	$ 108,898	$ 2,632