Organization and Summary of Significant Accounting Policies (Schedule of Effects of Change in Accounting for Inventory on the Statement of Income (Loss)) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	$ 406,829	$ 406,081	$ 376,158
Net income	$ 48,283	$ 46,320	$ 53,412
Basic earnings per share (in dollars per share)	$ 2.68	$ 2.52	$ 2.94
Diluted earnings per share (in dollars per share)	$ 2.65	$ 2.48	$ 2.86
Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales			$ 376,972
Net income			$ 52,883
Basic earnings per share (in dollars per share)			$ 2.91
Diluted earnings per share (in dollars per share)			$ 2.83
Pro Forma
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales			$ 376,158
Net income			$ 53,412
Basic earnings per share (in dollars per share)			$ 2.94
Diluted earnings per share (in dollars per share)			$ 2.86
Restatement Adjustment | Change from LIFO to FIFO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales			$ (814)
Net income			$ 529
Basic earnings per share (in dollars per share)			$ 0.03
Diluted earnings per share (in dollars per share)			$ 0.03