Consolidated Statements of Changes in Stockholders' Equity - 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
Balances	$ 39	$ 100,926	$ 1,619,816	$ (218,089)	$ (23,373)	$ (18,042)	$ 1,461,277
Balance at Dec. 31, 2017	39	100,926	1,619,816	(218,089)	(23,373)	(18,042)	1,461,277
Net income (loss)	0	0	0	(26,563)	0	0	(26,563)
Change in accounting for marketable equity securities	0	0	0	1,289	(1,289)	0	0
Stock issued to directors	0	40	553	0	0	0	593
Common stock issued for cash, net of offering costs	0	641	6,105	0	0	0	6,746
Series B Preferred Stock dividends declared				(552)			(552)
Stock issued for 401(k) match	0	267	3,438	0	0	0	3,705
Restricted stock units granted			5,649				5,649
Common stock and warrants issued for purchase of another company	0	18,819	233,725	0	0	0	252,544
Common stock dividends declared	0	0	0	(4,393)	0	0	(4,393)
Common stock issued for employee incentive compensation	0	309	4,554	0	0	(1,308)	3,555
Common stock issued to pension plans	0	684	6,911	0	0	0	7,595
Restricted stock unit distributions	0	270	(270)	0	0	(1,386)	(1,386)
Other comprehensive income (loss)	0	0	0	0	(17,807)	0	(17,807)
Balances	39	100,926	1,619,816	(218,089)	(23,373)	(18,042)	1,461,277
Balances	39	121,956	1,880,481	(248,308)	(42,469)	(20,736)	1,690,963
Balance at Dec. 31, 2018	39	121,956	1,880,481	(248,308)	(42,469)	(20,736)	1,690,963
Net income (loss)	0	0	0	(99,557)	0	0	(99,557)
Stock issued to directors	0	63	392	0	0	0	455
Common stock issued for cash, net of offering costs	0	5,353	43,666	0	0	0	49,019
Series B Preferred Stock dividends declared	0	0	0	(552)	0	0	(552)
Stock issued for 401(k) match	0	470	3,392	0	0	0	3,862
Restricted stock units granted	0	0	5,213	0	0	0	5,213
Common stock dividends declared	0	0	0	(4,914)	0	0	(4,914)
Common stock issued for employee incentive compensation	0	899	7,375	0	0	(1,595)	6,679
Common stock issued to pension plans	0	596	3,004	0	0	0	3,600
Restricted stock unit distributions	0	291	(291)	0	0	(636)	(636)
Other comprehensive income (loss)	0	0	0	0	5,159	0	5,159
Adjustment to fair value of warrants issued for purchase of another company	0	0	(325)	0	0	0	(325)
Common stock issued for prepayment of debt	0	2,664	30,793	0	0	0	33,457
Balances	39	121,956	1,880,481	(248,308)	(42,469)	(20,736)	1,690,963
Balances	39	132,292	1,973,700	(353,331)	(37,310)	(22,967)	1,692,423
Balance at Dec. 31, 2019	39	132,292	1,973,700	(353,331)	(37,310)	(22,967)	1,692,423
Net income (loss)	0	0	0	(16,790)	0	0	(16,790)
Stock issued to directors	0	97	1,389	0	0	0	1,486
Series B Preferred Stock dividends declared	0	0	0	(552)	0	0	(552)
Stock issued for 401(k) match	0	397	4,227	0	0	0	4,624
Restricted stock units granted	0	0	4,975	0	0	0	4,975
Common stock dividends declared	0	0	0	(8,600)	0	0	(8,600)
Common stock issued for employee incentive compensation	0	700	4,396	0	0	(1,266)	3,830
Common stock issued to pension plans	0	717	15,315	0	0	0	16,032
Restricted stock unit distributions	0	426	(426)	0	0	(1,479)	(1,479)
Other comprehensive income (loss)	0	0	0	0	4,421	0	4,421
Balances	39	132,292	1,973,700	(353,331)	(37,310)	(22,967)	1,692,423
Treasury shares issued to charitable foundation	0	0	0	(246)	0	2,216	1,970
Balances	$ 39	$ 134,629	$ 2,003,576	$ (379,519)	$ (32,889)	$ (23,496)	$ 1,702,340