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, 2018		$ 502,840	$ 4,904	$ 6,099,940	$ 297,202	$ (161,998)	$ (87,653)
Shares issued for restricted stock awards, net of forfeitures				(15,058)		15,058
Compensation expense related to restricted stock awards				7,910
Net income	$ 97,577				97,577
Dividends paid on common stock					(79,340)
Dividends paid on preferred stock	(8,207)				(8,207)
Purchase of common stock						(74,788)
Other comprehensive (loss) income, net of tax							30,683
Balance at end of year at Mar. 31, 2019	6,629,070	502,840	4,904	6,092,792	307,232	(221,728)	(56,970)
Balance at beginning of year at Dec. 31, 2019	6,711,694	502,840	4,904	6,115,487	342,023	(220,717)	(32,843)
Shares issued for restricted stock awards, net of forfeitures				(22,198)		22,198
Compensation expense related to restricted stock awards				8,251
Net income	100,328				100,328
Dividends paid on common stock					(79,332)
Dividends paid on preferred stock	(8,207)				(8,207)
Effect of adopting | ASU No. 2016-13					(10,468)
Purchase of common stock						(37,159)
Other comprehensive (loss) income, net of tax							(47,722)
Balance at end of year at Mar. 31, 2020	$ 6,637,385	$ 502,840	$ 4,904	$ 6,101,540	$ 344,344	$ (235,678)	$ (80,565)