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	327,454				323,890			3,564
Other comprehensive income (loss)	(125,316)						(125,316)
Distributions to non-controlling interest	(471)							(471)
Purchase of treasury stock	(39,575)					(39,575)
Issuance of stock, under purchase and equity compensation plans	(10)			(20,884)		20,874
Stock-based compensation	9,555			9,555
Cash dividends per share, Common Stock, Cash	(75,261)				(75,261)
Dividends per share, Preferred Stock, Cash	(6,750)				(6,750)
Balance at Sep. 30, 2018	2,807,810	144,784	535,407	1,804,031	493,641	(33,174)	(141,596)	4,717
Balance at Jun. 30, 2018	2,771,383	144,784	535,407	1,804,057	408,374	(15,854)	(108,781)	3,396
Net income	114,069				112,576			1,493
Other comprehensive income (loss)	(32,815)						(32,815)
Distributions to non-controlling interest	(172)							(172)
Purchase of treasury stock	(20,506)					(20,506)
Issuance of stock, under purchase and equity compensation plans	(1)			(3,187)		3,186
Stock-based compensation	3,161			3,161
Cash dividends per share, Common Stock, Cash	(25,059)				(25,059)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Sep. 30, 2018	2,807,810	144,784	535,407	1,804,031	493,641	(33,174)	(141,596)	4,717
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	315,434				314,351			1,083
Other comprehensive income (loss)	208,842						208,842
Distributions to non-controlling interest	(3,520)							(3,520)
Purchase of treasury stock	(119,970)					(119,970)
Accelerated Share Repurchases, Initial Price Paid	(150,000)			(37,500)		(112,500)
Issuance of stock, under purchase and equity compensation plans	(3)			(15,046)		15,043
Stock-based compensation	10,365			10,365
Cash dividends per share, Common Stock, Cash	(85,533)				(85,533)
Dividends per share, Preferred Stock, Cash	(6,750)				(6,750)
Balance at Sep. 30, 2019	3,106,014	144,784	559,432	2,042,643	463,231	(251,663)	144,173	3,414
Balance at Jun. 30, 2019	3,171,363	144,784	559,432	2,077,491	384,232	(106,106)	108,898	2,632
Net income	110,080				109,242			838
Other comprehensive income (loss)	35,275						35,275
Distributions to non-controlling interest	(56)							(56)
Purchase of treasury stock	(33,891)					(33,891)
Accelerated Share Repurchases, Initial Price Paid	(150,000)			(37,500)		(112,500)
Issuance of stock, under purchase and equity compensation plans	0			(834)		834
Stock-based compensation	3,486			3,486
Cash dividends per share, Common Stock, Cash	(27,993)				(27,993)
Dividends per share, Preferred Stock, Cash	(2,250)				(2,250)
Balance at Sep. 30, 2019	$ 3,106,014	$ 144,784	$ 559,432	$ 2,042,643	$ 463,231	$ (251,663)	$ 144,173	$ 3,414