Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	PREFERRED STOCK (Par Value: $0.01):	COMMON STOCK (Par Value: $0.01):	PAID-IN CAPITAL IN EXCESS OF PAR:	RETAINED EARNINGS:	TREASURY STOCK, AT COST:	ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAX:
Balance at beginning of year at Dec. 31, 2017	$ 6,795,376	$ 502,840	$ 4,891	$ 6,072,559	$ 237,868	$ (7,615)	$ (15,167)
Balance at beginning of year (in shares) at Dec. 31, 2017			488,490,352
Shares issued for restricted stock, net of forfeitures			$ 13	(8,879)		8,866
Shares issued for restricted stock, net of forfeitures (in shares)			2,039,603
Compensation expense related to restricted stock awards	28,069			28,069
Net income	320,678				320,678
Dividends paid on common stock	(249,968)				(249,968)
Dividends paid on preferred stock	(24,621)				(24,621)
Effect of adopting | ASU No. 2016-01	260				260
Effect of adopting | ASU No. 2018-02					2,546		(2,546)
Purchase of common stock	(2,428)					(2,428)
Purchase of common stock (in shares)			(188,091)
Other comprehensive income (loss), net of tax	(73,351)						(73,351)
Balance at end of year at Sep. 30, 2018	6,794,015	502,840	$ 4,904	6,091,749	286,763	(1,177)	(91,064)
Balance at end of year (in shares) at Sep. 30, 2018			490,341,864
Balance at beginning of year at Jun. 30, 2018	6,789,352	502,840	$ 4,904	6,082,394	271,559	(757)	(71,588)
Balance at beginning of year (in shares) at Jun. 30, 2018			490,379,705
Compensation expense related to restricted stock awards	9,355			9,355
Net income	106,772				106,772
Dividends paid on common stock	(83,361)				(83,361)
Dividends paid on preferred stock	(8,207)				(8,207)
Purchase of common stock	(420)					(420)
Purchase of common stock (in shares)			(37,841)
Other comprehensive income (loss), net of tax	(19,476)						(19,476)
Balance at end of year at Sep. 30, 2018	6,794,015	502,840	$ 4,904	6,091,749	286,763	(1,177)	(91,064)
Balance at end of year (in shares) at Sep. 30, 2018			490,341,864
Balance at beginning of year at Dec. 31, 2018	6,655,235	502,840	$ 4,904	6,099,940	297,202	(161,998)	(87,653)
Balance at beginning of year (in shares) at Dec. 31, 2018			473,536,604
Shares issued for restricted stock, net of forfeitures				(16,501)		16,501
Shares issued for restricted stock, net of forfeitures (in shares)			1,665,028
Compensation expense related to restricted stock awards	23,937			23,937
Net income	293,869				293,869
Dividends paid on common stock	(238,043)				(238,043)
Dividends paid on preferred stock	(24,621)				(24,621)
Purchase of common stock	(75,172)					(75,172)
Purchase of common stock (in shares)			(7,850,772)
Other comprehensive income (loss), net of tax	59,802						59,802
Balance at end of year at Sep. 30, 2019	6,695,007	502,840	$ 4,904	6,107,376	328,407	(220,669)	(27,851)
Balance at end of year (in shares) at Sep. 30, 2019			467,350,860
Balance at beginning of year at Jun. 30, 2019	6,674,678	502,840	$ 4,904	6,099,474	316,921	(220,546)	(28,915)
Balance at beginning of year (in shares) at Jun. 30, 2019			467,358,939
Shares issued for restricted stock, net of forfeitures				(222)		222
Shares issued for restricted stock, net of forfeitures (in shares)			22,980
Compensation expense related to restricted stock awards	8,124			8,124
Net income	99,046				99,046
Dividends paid on common stock	(79,353)				(79,353)
Dividends paid on preferred stock	(8,207)				(8,207)
Purchase of common stock	(345)					(345)
Purchase of common stock (in shares)			(31,059)
Other comprehensive income (loss), net of tax	1,064						1,064
Balance at end of year at Sep. 30, 2019	$ 6,695,007	$ 502,840	$ 4,904	$ 6,107,376	$ 328,407	$ (220,669)	$ (27,851)
Balance at end of year (in shares) at Sep. 30, 2019			467,350,860