INCOME TAXES: Carry forwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective income tax rate differs from the statutory rate
U.S. statutory rate (as a percent)	35.00%	35.00%	35.00%
State income taxes, net (as a percent)	1.10%	1.00%	1.00%
Exempt municipal bond interest (as a percent)	(0.10%)	(0.50%)	(0.40%)
Foreign tax rates (as a percent)	(1.30%)	(1.50%)	(2.00%)
Qualified domestic production activities deduction (as a percent)	(2.60%)	(2.80%)	(2.20%)
Tax credits receivable (as a percent)	(1.20%)	(0.60%)	(0.90%)
Adjustment of deferred tax balances (as a percent)	0.20%	1.90%	(1.10%)
Reserve for uncertain tax benefits (as a percent)	(2.10%)		(0.70%)
Other, net (as a percent)	(0.40%)	(1.40%)	(0.70%)
Effective income tax rate (as a percent)	28.60%	31.10%	28.00%
Foreign subsidiaries' undistributed earnings	$ 3,529	$ 5,393
Estimated federal income tax liability on foreign subsidiaries' undistributed earnings (as a percent)	30.00%
Cash and short term investments held by foreign subsidiary	$ 15,265	15,986
Portion of unrecognized tax benefits that, if recognized, would favorably affect annual effective income tax rate	2,737	4,805
Interest and penalties included in liability for uncertain tax positions	421	1,591
Reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	6,993	6,010	$ 6,677
Increases in tax positions for the current year	812	1,827	1,163
Increases in tax positions for new uncertain tax position		609
Reductions in tax positions for lapse of statute of limitations	(865)	(1,050)	(867)
Reductions in tax positions relating to settlements with taxing authorities	(772)	(403)	(140)
Decreases in prior period unrecognized tax benefits	(1,488)
Reductions in tax positions for effective settlements			(823)
Unrecognized tax benefits at the end of the period	4,680	$ 6,993	$ 6,010
Canada
Effective income tax rate differs from the statutory rate
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2028	4,081
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2029	3,439
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2031	602
Spain
Effective income tax rate differs from the statutory rate
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2026	273
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2027	58
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2028	200
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2029	99
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2030	306
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2031	399
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2032	288
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2033	$ 211