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, 2017	$ 5,396	$ 107,176	$ 1,414,485	$ (525,422)	$ (149,334)
Beginning balance (in shares) at Dec. 31, 2017				10,759,291
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	38,194	$ 0	0	$ 38,194
Other comprehensive income (loss)	0	0	0	0	23,864
Cash dividends paid	0	0	(14,274)	0	0
Share-based compensation	0	1,254	0	0	0
Stock options exercised	0	(38)	0	$ 98	0
Stock options exercised (in shares)				(2,000)
Non-vested stock issued upon vesting	0	(4,842)	0	$ 4,842	0
Non-vested stock issued upon vesting (in shares)				(99,152)
Benefit plans	0	350	0	$ 769	0
Benefit plans (in shares)				(15,126)
Purchase of treasury stock	0	0	0	$ (72,704)	0
Purchase of treasury stock (in shares)				1,000,000
Other	0	(801)	418	$ (1,975)	0
Other (in shares)				40,430
Ending balance at Mar. 31, 2018	5,396	103,099	1,438,823	$ (594,392)	(125,470)
Ending balance (in shares) at Mar. 31, 2018				11,683,443
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 income (loss)	0	0	0	0	(716)
Cash dividends paid	0	0	(15,218)	0	0
Share-based compensation	0	687	0	0	0
Non-vested stock issued upon vesting	0	(1,784)	0	$ 1,784	0
Non-vested stock issued upon vesting (in shares)				(35,016)
Benefit plans	0	72	0	$ 948	0
Benefit plans (in shares)				(18,597)
Other	0	(153)	0	$ (650)	0
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