Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2019	$ 39	$ 132,292	$ 1,973,700	$ (365,186)	$ (37,310)	$ (22,967)	$ 1,680,568
Net income (loss)	0	0	0	(31,213)	0	0	(31,213)
Restricted stock units granted	0	0	2,430	0	0	0	2,430
Restricted stock unit distributions	0	426	(426)	0	0	(1,479)	(1,479)
Common stock dividends declared	0	0	0	(2,622)	0	0	(2,622)
Series B Preferred Stock dividends declared	0	0	0	(276)	0	0	(276)
Common stock issued for 401(k) match	0	240	1,992	0	0	0	2,232
Other comprehensive income (loss)	0	0	0	0	(8,951)	0	(8,951)
Balances at Jun. 30, 2020	39	133,699	1,982,400	(399,543)	(46,261)	(23,496)	1,646,838
Common stock issued for employee incentive compensation	0	699	4,396	0	0	(1,266)	3,829
Common stock issued to pension plans	0	42	308	0	0	0	350
Treasury shares issued to charitable foundation	0	0	0	(246)	0	2,216	1,970
Balance at Mar. 31, 2020	39	132,381	1,976,033	(383,813)	(56,645)	(22,967)	1,645,028
Net income (loss)	0	0	0	(14,028)	0	0	(14,028)
Restricted stock units granted	0	0	1,211	0	0	0	1,211
Restricted stock unit distributions	0	426	(426)	0	0	(1,479)	(1,479)
Common stock dividends declared	0	0	0	(1,318)	0	0	(1,318)
Series B Preferred Stock dividends declared	0	0	0	(138)	0	0	(138)
Common stock issued for 401(k) match	0	151	878	0	0	0	1,029
Other comprehensive income (loss)	0	0	0	0	10,384	0	10,384
Balances at Jun. 30, 2020	39	133,699	1,982,400	(399,543)	(46,261)	(23,496)	1,646,838
Common stock issued for employee incentive compensation	0	699	4,396	0	0	(1,266)	3,829
Common stock issued to pension plans	0	42	308	0	0	0	350
Treasury shares issued to charitable foundation	0	0	0	(246)	0	2,216	1,970
Balance at Dec. 31, 2020	39	134,629	2,003,576	(391,374)	(32,889)	(23,496)	1,690,485
Net income (loss)	0	0	0	19,756	0	0	19,756
Restricted stock units granted	0	0	1,459	0	0	0	1,459
Restricted stock unit distributions	0	413	(413)	0	0	(4,525)	(4,525)
Common stock dividends declared	0	0	0	(10,715)	0	0	(10,715)
Series B Preferred Stock dividends declared	0	0	0	(276)	0	0	(276)
Common stock issued for 401(k) match	0	96	2,306	0	0	0	2,402
Common stock issued to directors	0	52	1,792	0	0	0	1,844
Other comprehensive income (loss)	0	0	0	0	3,452	0	3,452
Balances at Jun. 30, 2021	39	136,065	2,024,645	(382,609)	(29,437)	(28,021)	1,720,682
Common stock issued to pension plans	0	875	15,925	0	0	0	16,800
Balance at Mar. 31, 2021	39	135,546	2,021,072	(377,229)	(31,057)	(23,496)	1,724,875
Net income (loss)	0	0	0	785	0	0	785
Restricted stock units granted	0	0	959	0	0	0	959
Restricted stock unit distributions	0	413	(413)	0	0	(4,525)	(4,525)
Common stock dividends declared	0	0	0	(6,027)	0	0	(6,027)
Series B Preferred Stock dividends declared	0	0	0	(138)	0	0	(138)
Common stock issued for 401(k) match	0	54	1,235	0	0	0	1,289
Common stock issued to directors	0	52	1,792	0	0	0	1,844
Other comprehensive income (loss)	0	0	0	0	1,620	0	1,620
Balances at Jun. 30, 2021	$ 39	$ 136,065	$ 2,024,645	$ (382,609)	$ (29,437)	$ (28,021)	$ 1,720,682