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	234,083				234,083
Other comprehensive income (loss)	(99,980)					(99,980)
Stock option exercises/stock unit conversions (28,832 shares QTD and 144,262 shares YTD in 2022 and 114,252 shares QTD and 628,076 shares YTD in 2021)	36,682				(25,567)		62,249
Stock compensation expense recognized in earnings	5,771			5,771
Purchase of treasury stock (7,459 shares YTD in 2022 and 11,625 shares YTD in 2021)	(1,288)						(1,288)
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 $22.25 per share which is equivalent to approximately $0.28 and $0.56 per depository share QTD and YTD in 2022, respectively and $11.13 and $25.46 per share which is equivalent to approximately $0.28 and $0.64 per depository share QTD and YTD in 2021, respectively)	(3,820)				(3,820)
Cash dividends – common stock ($0.75 per share QTD and $1.50 per share YTD in 2022 and $0.72 per share QTD and $1.44 per share YTD in 2021)	(92,396)				(92,396)
Total shareholders’ equity at end of period at Jun. 30, 2021	4,373,817	145,452	642	1,002,939	2,862,966	412,990	(51,172)
Total shareholders’ equity at beginning of period at Mar. 31, 2021	4,267,918	145,452	642	999,694	2,797,064	387,748	(62,682)
Net income	118,068				118,068
Other comprehensive income (loss)	25,242					25,242
Stock option exercises/stock unit conversions (28,832 shares QTD and 144,262 shares YTD in 2022 and 114,252 shares QTD and 628,076 shares YTD in 2021)	7,285				(4,225)		11,510
Stock compensation expense recognized in earnings	3,245			3,245
Cash dividends – preferred stock (approximately $11.13 and $22.25 per share which is equivalent to approximately $0.28 and $0.56 per depository share QTD and YTD in 2022, respectively and $11.13 and $25.46 per share which is equivalent to approximately $0.28 and $0.64 per depository share QTD and YTD in 2021, respectively)	(1,669)				(1,669)
Cash dividends – common stock ($0.75 per share QTD and $1.50 per share YTD in 2022 and $0.72 per share QTD and $1.44 per share YTD in 2021)	(46,272)				(46,272)
Total shareholders’ equity at end of period at Jun. 30, 2021	4,373,817	145,452	642	1,002,939	2,862,966	412,990	(51,172)
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	218,216				218,216
Other comprehensive income (loss)	(1,221,524)					(1,221,524)
Stock option exercises/stock unit conversions (28,832 shares QTD and 144,262 shares YTD in 2022 and 114,252 shares QTD and 628,076 shares YTD in 2021)	6,490				(4,777)		11,267
Stock compensation expense recognized in earnings	5,530			5,530
Purchase of treasury stock (7,459 shares YTD in 2022 and 11,625 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 $22.25 per share which is equivalent to approximately $0.28 and $0.56 per depository share QTD and YTD in 2022, respectively and $11.13 and $25.46 per share which is equivalent to approximately $0.28 and $0.64 per depository share QTD and YTD in 2021, respectively)	(3,338)				(3,338)
Cash dividends – common stock ($0.75 per share QTD and $1.50 per share YTD in 2022 and $0.72 per share QTD and $1.44 per share YTD in 2021)	(96,958)				(96,958)
Total shareholders’ equity at end of period at Jun. 30, 2022	3,346,975	145,452	642	1,015,451	3,070,109	(874,206)	(10,473)
Total shareholders’ equity at beginning of period at Mar. 31, 2022	3,776,292	145,452	642	1,012,033	3,002,642	(371,790)	(12,687)
Net income	119,114				119,114
Other comprehensive income (loss)	(502,416)					(502,416)
Stock option exercises/stock unit conversions (28,832 shares QTD and 144,262 shares YTD in 2022 and 114,252 shares QTD and 628,076 shares YTD in 2021)	751				(1,463)		2,214
Stock compensation expense recognized in earnings	3,418			3,418
Cash dividends – preferred stock (approximately $11.13 and $22.25 per share which is equivalent to approximately $0.28 and $0.56 per depository share QTD and YTD in 2022, respectively and $11.13 and $25.46 per share which is equivalent to approximately $0.28 and $0.64 per depository share QTD and YTD in 2021, respectively)	(1,669)				(1,669)
Cash dividends – common stock ($0.75 per share QTD and $1.50 per share YTD in 2022 and $0.72 per share QTD and $1.44 per share YTD in 2021)	(48,515)				(48,515)
Total shareholders’ equity at end of period at Jun. 30, 2022	$ 3,346,975	$ 145,452	$ 642	$ 1,015,451	$ 3,070,109	$ (874,206)	$ (10,473)