Organization and Summary of Significant Accounting Policies (Earning Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Net income	$ 80,459	$ 48,283	$ 46,320
Weighted-average shares outstanding - basic	18,154,000	17,991,000	18,371,000
Effect of dilutive stock options (in shares)	393,000	232,000	309,000
Denominator for diluted earnings per share - Adjusted weighted-average shares and assumed conversions (shares)	18,547,000	18,223,000	18,680,000
Basic earnings per share (in dollars per share)	$ 4.43	$ 2.68	$ 2.52
Diluted earnings per share (in dollars per share)	$ 4.34	$ 2.65	$ 2.48
Antidilutive securities excluded from computation of earnings per share (shares)	0	0	44,350