Organization and Summary of Significant Accounting Policies, Unrealized Loss Position (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Continuous unrealized loss position, fair value [Abstract]
In Loss Position Less Than 12 Months, Fair Value	$ 37,043	$ 17,823
In Loss Position More Than 12 Months, Fair Value	8,990	8,542
Total In Loss Position, Fair Value	46,033	26,365
Continuous unrealized loss position, unrealized losses [Abstract]
In Loss Position Less Than 12 Months, Unrealized Losses	(30)	(12)
In Loss Position More Than 12 Months, Unrealized Losses	(23)	(12)
Total In Loss Position, Unrealized Losses	(53)	(24)
Certificates of Deposit [Member]
Continuous unrealized loss position, fair value [Abstract]
In Loss Position Less Than 12 Months, Fair Value	1,679	3,776
In Loss Position More Than 12 Months, Fair Value	1,196	0
Total In Loss Position, Fair Value	2,875	3,776
Continuous unrealized loss position, unrealized losses [Abstract]
In Loss Position Less Than 12 Months, Unrealized Losses	(1)	(2)
In Loss Position More Than 12 Months, Unrealized Losses	(4)	0
Total In Loss Position, Unrealized Losses	(5)	(2)
Corporate Notes and Bonds [Member]
Continuous unrealized loss position, fair value [Abstract]
In Loss Position Less Than 12 Months, Fair Value	35,364	14,047
In Loss Position More Than 12 Months, Fair Value	7,794	8,542
Total In Loss Position, Fair Value	43,158	22,589
Continuous unrealized loss position, unrealized losses [Abstract]
In Loss Position Less Than 12 Months, Unrealized Losses	(29)	(10)
In Loss Position More Than 12 Months, Unrealized Losses	(19)	(12)
Total In Loss Position, Unrealized Losses	$ (48)	$ (22)