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, 2015	$ 2,367,418	$ 144,784	$ 489,862	$ 1,337,677	$ 383,313	$ (26,116)	$ 32,470	$ 5,428
Net income	204,480				203,812			668
Other comprehensive income (loss)	88,612						88,612
Distributions to non-controlling interest	(704)							(704)
Purchase of treasury stock	(38,476)					(38,476)
Issuance of stock under purchase and equity compensation plans	(3)			(14,057)		14,054
Excess (net) tax benefit related to equity compensation plans	2,629			2,629
Stock-based compensation	8,901			8,901
Cash dividends per share, Common Stock, Cash	(65,294)				(65,294)
Dividends per share, Preferred Stock, Cash	(6,750)				(6,750)
Balance at Sep. 30, 2016	2,560,813	144,784	489,862	1,335,150	515,081	(50,538)	121,082	5,392
Balance at Dec. 31, 2016	2,501,132	144,784	510,015	1,552,454	292,849	(15,294)	10,975	5,349
Adoption of ASU 2016-09	1,297			3,441	(2,144)
Net income	224,917				225,028			(111)
Other comprehensive income (loss)	56,086						56,086
Distributions to non-controlling interest	(1,305)							(1,305)
Purchase of treasury stock	(11,320)					(11,320)
Issuance of stock under purchase and equity compensation plans	(7)			(16,726)		16,719
Stock-based compensation	9,149			9,149
Cash dividends per share, Common Stock, Cash	(68,722)				(68,722)
Dividends per share, Preferred Stock, Cash	(6,750)				(6,750)
Balance at Sep. 30, 2017	$ 2,704,477	$ 144,784	$ 510,015	$ 1,548,318	$ 440,261	$ (9,895)	$ 67,061	$ 3,933