General (Details 6) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Short-term and long-term investments
Other-than-temporary unrealized losses	$ 0	$ 0
Realized loss on sale of investments	50,000
Amortized Cost	171,322,000	208,468,000
Gross Unrealized Gains	67,000	20,000
Gross Unrealized Losses	(34,000)	(175,000)
Estimated Fair Value	171,355,000	208,313,000
U.S. Government and agency securities
Short-term and long-term investments
Amortized Cost	2,078,000	1,129,000
Gross Unrealized Gains	1,000
Gross Unrealized Losses	(1,000)
Estimated Fair Value	2,078,000	1,129,000
Obligations of government-sponsored enterprises
Short-term and long-term investments
Amortized Cost	8,707,000	8,441,000
Gross Unrealized Gains	2,000	2,000
Gross Unrealized Losses	(2,000)	(3,000)
Estimated Fair Value	8,707,000	8,440,000
Corporate debt securities
Short-term and long-term investments
Amortized Cost	159,387,000	198,748,000
Gross Unrealized Gains	64,000	18,000
Gross Unrealized Losses	(31,000)	(172,000)
Estimated Fair Value	159,420,000	198,594,000
Certificates of deposit
Short-term and long-term investments
Amortized Cost	1,150,000	150,000
Estimated Fair Value	$ 1,150,000	$ 150,000