Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net earnings	$ 39,940,000	$ 52,959,000	$ 44,564,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Provision for depreciation	4,052,000	7,258,000	13,962,000
Intangibles amortization	2,167,000	2,630,000	721,000
Deferred income tax provision (benefit)	(121,000)	(4,001,000)	6,360,000
Net loss (gain) and impairment on divestiture of businesses	2,528,000
Net loss (gain) and impairment on divestiture of businesses from discontinued operations		(11,413,000)
Net gain on involuntary conversion of machinery and equipment		(2,713,000)	(968,000)
Loss on disposal and impairment of property, plant and equipment	163,000	248,000	434,000
Provision for doubtful accounts	458,000	70,000	1,000
Noncash retirement plan expense	698,000	675,000	782,000
Other	229,000	238,000	217,000
Changes in operating accounts:
Accounts receivable	11,546,000	1,848,000	(13,539,000)
Inventories	6,821,000	(8,730,000)	(7,528,000)
Other assets and current assets	4,067,000	(806,000)	5,148,000
Accounts payable and accrued liabilities	6,066,000	(11,462,000)	12,145,000
Federal and state income taxes receivable/payable	(2,366,000)	(2,523,000)	4,077,000
Net cash provided by operating activities	76,248,000	24,278,000	66,376,000
Cash flows from investing activities:
Marketable securities purchased	(163,271,000)	(192,584,000)	(86,119,000)
Marketable securities - maturities and sales	173,060,000	132,752,000	33,863,000
Proceeds from divestiture of business, net of cash paid	9,410,000	64,033,000
Purchase of property, plant and equipment	(8,686,000)	(7,396,000)	(6,950,000)
Notes issued	(2,300,000)		(2,419,000)
Proceeds from insurnace settlement	2,630,000	2,104,000	987,000
Acquisition of intangible assets		(1,000,000)	(211,000)
Sale of property, plant and equipment	1,000	1,000	3,000
Net cash provided by (used in) investing activities	10,844,000	(2,090,000)	(60,846,000)
Cash flows from financing activities:
Dividends paid	(41,989,000)	(38,405,000)	(35,161,000)
Proceeds from sale of treasury stock	528,000	519,000	443,000
Other	(6,000)	(114,000)
Net cash used in financing activities	(41,467,000)	(38,000,000)	(34,718,000)
Net increase (decrease) in cash and cash equivalents	45,625,000	(15,812,000)	(29,188,000)
Cash and cash equivalents at beginning of year	11,222,000	27,034,000	56,222,000
Cash and cash equivalents at end of year	56,847,000	11,222,000	27,034,000
Supplemental disclosures of cash flow information:
Income taxes	$ 14,968,000	$ 32,837,000	$ 17,278,000