Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]
Total shareholders’ equity at beginning of period at Dec. 31, 2020	$ 4,293,016	$ 145,452	$ 642	$ 997,168	$ 2,750,723	$ 512,970	$ (113,939)
Net income	342,058				342,058
Other comprehensive income (loss)	(162,687)					(162,687)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	37,810				(26,652)		64,462
Stock compensation expense recognized in earnings	7,756			7,756
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)	(1,342)						(1,342)
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares YTD in 2021 )	1,749				(57)		1,806
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(5,488)				(5,488)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(140,510)				(140,510)
Total shareholders’ equity at end of period at Sep. 30, 2021	4,372,362	145,452	642	1,004,924	2,920,074	350,283	(49,013)
Total shareholders’ equity at beginning of period at Jun. 30, 2021	4,373,817	145,452	642	1,002,939	2,862,966	412,990	(51,172)
Net income	107,975				107,975
Other comprehensive income (loss)	(62,707)					(62,707)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	1,128				(1,085)		2,213
Stock compensation expense recognized in earnings	1,985			1,985
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)	(54)						(54)
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(1,668)				(1,668)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(48,114)				(48,114)
Total shareholders’ equity at end of period at Sep. 30, 2021	4,372,362	145,452	642	1,004,924	2,920,074	350,283	(49,013)
Total shareholders’ equity at beginning of period at Dec. 31, 2021	4,439,555	145,452	642	1,009,921	2,956,966	347,318	(20,744)
Net income	387,976				387,976
Other comprehensive income (loss)	(1,876,243)					(1,876,243)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	11,760				(6,695)		18,455
Stock compensation expense recognized in earnings	8,703			8,703
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)	(996)						(996)
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares YTD in 2021 )	0
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(5,006)				(5,006)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(153,277)				(153,277)
Total shareholders’ equity at end of period at Sep. 30, 2022	2,812,472	145,452	642	1,018,624	3,179,964	(1,528,925)	(3,285)
Total shareholders’ equity at beginning of period at Jun. 30, 2022	3,346,975	145,452	642	1,015,451	3,070,109	(874,206)	(10,473)
Net income	169,760				169,760
Other comprehensive income (loss)	(654,719)					(654,719)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	5,270				(1,918)		7,188
Stock compensation expense recognized in earnings	3,173			3,173
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(1,668)				(1,668)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(56,319)				(56,319)
Total shareholders’ equity at end of period at Sep. 30, 2022	$ 2,812,472	$ 145,452	$ 642	$ 1,018,624	$ 3,179,964	$ (1,528,925)	$ (3,285)