CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Earnings Reinvested in the Business [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning balance at Dec. 31, 2018	$ 5,396	$ 101,663	$ 1,516,243	$ (597,800)	$ (165,555)	$ 859,947
Beginning balance (in shares) at Dec. 31, 2018				11,731,223
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	32,807	$ 0	0	32,807
Other comprehensive loss	0	0	0	0	(716)	(716)
Cash dividends paid	0	0	(15,218)	0	0	(15,218)
Share-based compensation	0	687	0	0	0	687
Non-vested stock issued upon vesting	0	(1,784)	0	$ 1,784	0	0
Non-vested stock issued upon vesting (in shares)				(35,016)
Benefit plans	0	72	0	$ 948	0	1,020
Benefit plans (in shares)				(18,597)
Other	0	(153)	0	$ (650)	0	(803)
Other (in shares)				12,769
Ending balance at Mar. 31, 2019	5,396	100,485	1,533,832	$ (595,718)	(166,271)	877,724
Ending balance (in shares) at Mar. 31, 2019				11,690,379
Beginning balance at Dec. 31, 2019	5,396	98,425	1,536,100	$ (595,324)	(163,008)	881,589
Beginning balance (in shares) at Dec. 31, 2019				11,682,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	20,773	$ 0	0	20,773
Other comprehensive loss	0	0	0	0	(44,353)	(44,353)
Cash dividends paid	0	0	(16,500)	0	0	(16,500)
Share-based compensation	0	1,177	0	0	0	1,177
Non-vested stock issued upon vesting	0	(724)	0	$ 724	0	0
Non-vested stock issued upon vesting (in shares)				(14,200)
Benefit plans	0	241	0	$ 833	0	1,074
Benefit plans (in shares)				(16,344)
Other	0	(39)	0	$ (210)	0	(249)
Other (in shares)				4,114
Ending balance at Mar. 31, 2020	5,396	99,080	1,539,520	$ (593,977)	(207,361)	842,658
Ending balance (in shares) at Mar. 31, 2020				11,656,206
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2016-13 | ASU 2016-13 [Member]	$ 0	$ 0	$ (853)	$ 0	$ 0	$ (853)