Income Taxes: Effective tax rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	$ 24,395	$ 13,927	$ 18,450
Income Tax Reconciliation, State and Local Income Taxes	2,661	981	1,126
Income Tax Reconciliation, Tax Credits	(5,861)	(1,591)	(1,974)
Income Tax Reconciliation, Tax Exempt Income	0	(3)	0
Income Tax Reconciliation, Deductions, Qualified Production Activities	107	104	(403)
Income Tax Reconciliation, Foreign Income Tax Rate Differential	$ 3,412	$ 39	$ (4,903)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes	3.90%	2.50%	2.10%
Effective Income Tax Rate Reconciliation, Tax Credits	(8.40%)	(4.00%)	(3.70%)
Effective Income Tax Rate Reconciliation, Tax Exempt Income	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deductions, Qualified Production Activities	0.10%	0.20%	(0.80%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential	4.90%	0.10%	(9.30%)
Effective Income Tax Rate, Continuing Operations	35.50%	33.80%	23.30%