Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series F Preferred Stock [Member]	Common Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Series F Preferred Stock [Member]	Treasury Stock, at cost [Member]	AOCI Attributable to Parent [Member]
Beginning Balance at Dec. 31, 2018	$ 2,886,515			$ 145,037	$ 937	$ 1,114,394	$ 1,828,303		$ (71,504)	$ (130,652)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	99,736						99,736
Other Comprehensive Income (Loss), Net of Tax	28,811									28,811
Dividends and dividend equivalents declared on common stock	(30,589)					0	(30,589)
Common Stock, Dividends, Per Share, Declared			$ 0.33
Dividends on preferred stock		$ (1,969)						$ (1,969)
Dividends on preferred stock (in dollars per share)		$ 328.125
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	2,976					0	904		2,072
Stock Issued During Period, Value, Stock Options Exercised	404					(1,287)			1,691
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(6,111)								6,111
Stock Repurchased During Period, Value	(13,003)								13,003
Ending Balance at Mar. 31, 2019	2,966,255			145,037	937	1,113,107	1,895,870		(86,855)	(101,841)
Beginning Balance at Dec. 31, 2019	3,207,770			145,037	937	1,113,250	2,061,352		(76,734)	(36,072)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,199						38,199
Other Comprehensive Income (Loss), Net of Tax	11,272									11,272
Dividends and dividend equivalents declared on common stock	(36,828)						(36,828)
Common Stock, Dividends, Per Share, Declared			$ 0.40
Dividends on preferred stock		$ (1,969)						$ (1,969)
Dividends on preferred stock (in dollars per share)		$ 328.125
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	2,609					(11,821)	0		14,430
Stock Issued During Period, Value, Stock Options Exercised	118					(105)			223
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(3,160)								3,160
Stock Repurchased During Period, Value	(76,556)								76,556
Ending Balance at Mar. 31, 2020	3,090,242			$ 145,037	$ 937	$ 1,101,324	2,009,541		$ (141,797)	$ (24,800)
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-08	$ (51,213)						$ (51,213)