CONSOLIDATED STATEMENTS OF Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$ 66,127	$ 62,860	$ 60,849
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation	20,388	20,758	20,050
Deferred income taxes	255	(946)	6,558
Net loss on step acquisition		529
Impairment of equity method investment			975
Loss from equity method investment			967
Amortization of marketable security premiums	3,105	3,261	3,035
Changes in operating assets and liabilities:
Accounts receivable	(8,929)	(2,007)	1,330
Other receivables	1,119	1,289	253
Inventories	7,530	(7,329)	503
Prepaid expenses and other assets	11,593	9,524	14,922
Accounts payable and accrued liabilities	3,839	(1,268)	418
Income taxes payable	(115)	(78)	(6,490)
Postretirement health care benefits	(903)	(1,289)	2,861
Deferred compensation and other liabilities	(12,936)	3,465	3,592
Net cash provided by operating activities	91,073	88,769	109,823
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash acquired in step acquisition		161
Change in restricted cash	1,149	224
Capital expenditures	(15,534)	(10,704)	(15,752)
Purchases of trading securities	(4,095)	(4,294)	(6,575)
Sales of trading securities	16,644	727	1,075
Purchase of available for sale securities	(61,951)	(54,882)	(66,324)
Sale and maturity of available for sale securities	55,264	38,309	39,613
Net cash used in investing activities	(8,523)	(30,459)	(47,963)
CASH FLOWS FROM FINANCING ACTIVITIES:
Shares purchased and retired	(33,004)	(25,020)	(23,143)
Dividends paid in cash	(20,775)	(19,241)	(14,282)
Repayment of bank loans	(133)	(403)
Net cash used in financing activities	(53,912)	(44,664)	(37,425)
Effect of exchange rate changes on cash	(2,601)	(1,821)	(14)
Increase (decrease) in cash and cash equivalents	26,037	11,825	24,421
Cash and cash equivalents at beginning of year	100,108	88,283	63,862
Cash and cash equivalents at end of year	126,145	100,108	88,283
Supplemental cash flow information:
Income taxes paid, net	24,940	26,599	24,225
Interest paid	17	34	21
Stock dividend issued	$ 57,220	$ 52,165	$ 48,925