Investments and Fair Value Measurements (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Cash, cash equivalents and investments [Abstract]
Cash	$ 25,769,000		$ 25,769,000		$ 24,852,000
Cash equivalents [Abstract]
Money market fund	24,000		24,000		109,000
Total cash and cash equivalents	25,793,000	27,723,000	25,793,000	27,723,000	24,961,000	30,634,000
Amortized Cost	47,136,000		47,136,000		45,682,000
Gross Unrealized Gain	1,397,000		1,397,000		1,933,000
Gross Unrealized (Loss)	(42,000)		(42,000)		(10,000)
Fair Value	48,491,000		48,491,000		47,605,000
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	13,971,000		13,971,000		10,569,000
Due after 1 through 5 years	7,372,000		7,372,000		10,152,000
Investments, amortized cost	21,343,000		21,343,000		20,721,000
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	15,366,000		15,366,000		12,499,000
Due after 1 through 5 years	7,332,000		7,332,000		10,145,000
Investments, fair value	22,698,000		22,698,000		22,644,000
Proceeds from sales of available-for-sale investments	319,000	0	665,000	0
Gross realized gains from sales of available-for-sale investments	302,000	0	626,000	0
Gain on sale of available for sale security			626,000		800,000
Unrealized gain, net of tax			1,400,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	7,811,000		7,811,000		7,898,000
Gross unrealized loss, in loss position less than twelve months			(41,000)		(9,000)
Fair value, in loss position greater than twelve months	4,583,000		4,583,000		4,431,000
Gross unrealized loss, in loss position greater than twelve months			(1,000)		(1,000)
Fair value, total in loss position	12,394,000		12,394,000		12,329,000
Gross unrealized loss, total in loss position			(42,000)		(10,000)
Minority Investments [Abstract]
Minority investments in unconsolidated privately-held companies	200,000		200,000		200,000
Other assets [Member]
Minority Investments [Abstract]
Investments in privately-held companies	12,100,000		12,100,000		10,900,000
Minority investments in unconsolidated privately-held companies	200,000		200,000		200,000
Certificates of deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	9,713,000		9,713,000		6,320,000
Gross Unrealized Gain	2,000		2,000		2,000
Gross Unrealized (Loss)	(16,000)		(16,000)		(4,000)
Fair Value	9,699,000		9,699,000		6,318,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	4,009,000		4,009,000		3,425,000
Gross unrealized loss, in loss position less than twelve months			(16,000)		(4,000)
Fair value, in loss position greater than twelve months	0		0		720,000
Gross unrealized loss, in loss position greater than twelve months			0		0
Fair value, total in loss position	4,009,000		4,009,000		4,145,000
Gross unrealized loss, total in loss position			(16,000)		(4,000)
Corporate bonds [Member]
Cash equivalents [Abstract]
Amortized Cost	11,543,000		11,543,000		14,276,000
Gross Unrealized Gain	2,000		2,000		8,000
Gross Unrealized (Loss)	(26,000)		(26,000)		(6,000)
Fair Value	11,519,000		11,519,000		14,278,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	3,802,000		3,802,000		4,473,000
Gross unrealized loss, in loss position less than twelve months			(25,000)		(5,000)
Fair value, in loss position greater than twelve months	4,583,000		4,583,000		3,711,000
Gross unrealized loss, in loss position greater than twelve months			(1,000)		(1,000)
Fair value, total in loss position	8,385,000		8,385,000		8,184,000
Gross unrealized loss, total in loss position			(26,000)		(6,000)
Corporate equity security [Member]
Cash equivalents [Abstract]
Amortized Cost	87,000		87,000		125,000
Gross Unrealized Gain	1,393,000		1,393,000		1,923,000
Gross Unrealized (Loss)	0		0		0
Fair Value	1,480,000		1,480,000		2,048,000
Total Investments [Member]
Cash equivalents [Abstract]
Amortized Cost	21,343,000		21,343,000		20,721,000
Gross Unrealized Gain	1,397,000		1,397,000		1,933,000
Gross Unrealized (Loss)	(42,000)		(42,000)		(10,000)
Fair Value	$ 22,698,000		$ 22,698,000		$ 22,644,000