Organization and Summary of Significant Accounting Policies (Changes in Allowance for Doubtful Accounts) (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Line Items]
Balance of allowance at beginning of year	$ 1,678	$ 2,254	$ 2,547
Increase in allowance charged to expense	197	(404)	(472)
Accounts charged against allowance	257	980	765
Balance of allowance at ending of year	$ 1,224	$ 1,678	$ 2,254