Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net earnings	$ 38,875,000	$ 47,968,000	$ 63,531,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Provision for depreciation	10,136,000	9,037,000	8,637,000
Loss (gain) on disposal and impairment of property, plant and equipment	5,843,000	10,000	(1,290,000)
Provision for doubtful accounts	5,629,000	1,037,000	50,000
Deferred income taxes	(4,792,000)	5,096,000	(399,000)
Intangibles amortization	1,049,000	0	0
Other	568,000	618,000	500,000
Changes in operating accounts:
Accounts receivable, net	(6,546,000)	16,936,000	1,194,000
Inventories	11,091,000	(10,284,000)	(14,557,000)
Other current assets	10,360,000	(6,729,000)	(5,604,000)
Accounts payable and accrued liabilities	(9,999,000)	(711,000)	6,138,000
Federal and state income taxes payable	128,000	(4,292,000)	(432,000)
Net cash provided by operating activities	62,342,000	58,686,000	57,768,000
Cash flows from investing activities:
Marketable securities purchased	(26,023,000)	(40,962,000)	(45,464,000)
Marketable securities - maturities and sales	29,767,000	82,521,000	62,109,000
Acquisition of property, plant and equipment	(13,584,000)	(15,003,000)	(17,972,000)
Notes issued	(3,500,000)	(220,000)	(1,580,000)
Sale of property, plant and equipment	8,000	6,000	1,365,000
Acquisition of businesses, net of cash acquired	(246,000)	(4,526,000)
Net cash provided by (used in) investing activities	(13,578,000)	21,816,000	(1,542,000)
Cash flows from financing activities:
Dividends paid	(86,106,000)	(56,665,000)	(55,889,000)
Other	784,000	439,000	408,000
Net cash used in financing activities	(85,322,000)	(56,226,000)	(55,481,000)
Net increase (decrease) in cash and cash equivalents	(36,558,000)	24,276,000	745,000
Cash and cash equivalents at beginning of period	73,995,000	49,719,000	48,974,000
Cash and cash equivalents at end of period	37,437,000	73,995,000	49,719,000
Supplemental disclosures of cash flow information:
Income taxes	$ 26,532,000	$ 26,686,000	$ 36,479,000