Investments and Fair Value Measurements (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Cash, cash equivalents and investments [Abstract]
Cash		$ 15,723,000		$ 15,723,000		$ 22,337,000
Cash equivalents [Abstract]
Certificates of deposit, amortized cost	[1]	10,462,000		10,462,000		6,454,000
Certificates of deposit, fair value	[1]	10,462,000		10,462,000		6,454,000
Money market fund						23,000
Total cash and cash equivalents		26,185,000	$ 25,793,000	26,185,000	$ 25,793,000	28,814,000	$ 24,961,000
Amortized Cost		45,263,000		45,263,000		48,267,000
Gross Unrealized Gain		230,000		230,000		712,000
Gross Unrealized (Loss)		(44,000)		(44,000)		(42,000)
Fair Value		45,449,000		45,449,000		48,937,000
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year		8,327,000		8,327,000		11,631,000
Due after 1 through 5 years		10,751,000		10,751,000		7,822,000
Investments, amortized cost		19,078,000		19,078,000		19,453,000
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year		8,551,000		8,551,000		12,340,000
Due after 1 through 5 years		10,713,000		10,713,000		7,783,000
Investments, fair value		19,264,000		19,264,000		20,123,000
Proceeds from sales of available-for-sale investments		0
Realized gain		0
Gross realized gains from sales of available-for-sale investments				859,000	626,000
GHI [Member]
Contractual maturities on investments, fair value basis [Abstract]
Unrealized gain, net of tax				227,000
IntelliEpi [Member]
Contractual maturities on investments, fair value basis [Abstract]
Proceeds from sales of available-for-sale investments			319,000	902,000	665,000
Investments in publicly-held companies		0		0
Available-for-sale investments, expenses			17,000	43,000	39,000
Gross realized gains from sales of available-for-sale investments			$ 302,000	859,000	$ 626,000
Auction Rate Securities [Member]
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value		0		0
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	[2]	10,053,000		10,053,000		10,195,000
Gross Unrealized Gain	[2]	3,000		3,000		1,000
Gross Unrealized (Loss)	[2]	(6,000)		(6,000)		(13,000)
Fair Value	[2]	10,050,000		10,050,000		10,183,000
Corporate Bonds [Member]
Cash equivalents [Abstract]
Amortized Cost		8,825,000		8,825,000		9,214,000
Gross Unrealized Gain						1,000
Gross Unrealized (Loss)		(38,000)		(38,000)		(29,000)
Fair Value		8,787,000		8,787,000		9,186,000
Corporate Equity Securities [Member]
Cash equivalents [Abstract]
Amortized Cost		200,000		200,000		44,000
Gross Unrealized Gain		227,000		227,000		710,000
Fair Value		427,000		427,000		754,000
Total Investments [Member]
Cash equivalents [Abstract]
Amortized Cost		19,078,000		19,078,000		19,453,000
Gross Unrealized Gain		230,000		230,000		712,000
Gross Unrealized (Loss)		(44,000)		(44,000)		(42,000)
Fair Value		$ 19,264,000		$ 19,264,000		$ 20,123,000

[1] Certificate of deposit with original maturities of less than 90 days.

[2] Certificate of deposit with original maturities of more than 90 days.