Investments and Fair Value Measurements (Details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Cash, cash equivalents and investments [Abstract]
Amortized Cost	$ 51,466,000		$ 40,776,000
Gross Unrealized Gain	19,000		7,000
Gross Unrealized (Loss)	(38,000)		(141,000)
Fair Value	51,447,000		40,642,000
Contractual maturities on investments, amortized cost basis
Due within 1 year	10,581,000		5,521,000
Due after 1 through 5 years	5,382,000		9,099,000
Investments, amortized cost	15,963,000		14,620,000
Contractual maturities on investments, fair value basis
Due within 1 year	10,577,000		5,505,000
Due after 1 through 5 years	5,367,000		8,981,000
Investments, fair value	15,944,000		14,486,000
Gross realized loss on available-for-sale securities	0	8,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	6,039,000		10,098,000
Fair value, in loss position greater than twelve months	1,717,000
Fair value, total in loss position	7,756,000		10,098,000
Gross unrealized loss, in loss position less than twelve months	(20,000)		(141,000)
Gross unrealized loss, in loss position greater than twelve months	(18,000)
Gross unrealized loss, total in loss position	(38,000)		(141,000)
Investment in privately held Companies [Abstract]
Minority investments in unconsolidated privately-held companies	392,000		392,000
Recurring [Member]
Assets:
Assets, fair value	23,957,000		15,343,000
Liabilities:
Liabilities, fair value	0		0
Recurring [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets:
Assets, fair value	8,013,000		857,000
Liabilities:
Liabilities, fair value	0		0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value	15,944,000		14,486,000
Liabilities:
Liabilities, fair value	0		0
Recurring [Member] | Cash equivalents and investments [Member] | Money market fund [Member]
Assets:
Assets, fair value	8,013,000		857,000
Recurring [Member] | Cash equivalents and investments [Member] | Money market fund [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets:
Assets, fair value	8,013,000		857,000
Recurring [Member] | Cash equivalents and investments [Member] | Money market fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value	0		0
Recurring [Member] | Cash equivalents and investments [Member] | Certificates of deposit [Member]
Assets:
Assets, fair value	6,881,000		3,563,000
Recurring [Member] | Cash equivalents and investments [Member] | Certificates of deposit [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets:
Assets, fair value	0		0
Recurring [Member] | Cash equivalents and investments [Member] | Certificates of deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value	6,881,000		3,563,000
Recurring [Member] | Cash equivalents and investments [Member] | US Treasury and agency securities [Member]
Assets:
Assets, fair value			1,199,000
Recurring [Member] | Cash equivalents and investments [Member] | US Treasury and agency securities [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets:
Assets, fair value			0
Recurring [Member] | Cash equivalents and investments [Member] | US Treasury and agency securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value			1,199,000
Recurring [Member] | Cash equivalents and investments [Member] | Corporate bonds [Member]
Assets:
Assets, fair value	9,063,000		9,724,000
Recurring [Member] | Cash equivalents and investments [Member] | Corporate bonds [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets:
Assets, fair value	0		0
Recurring [Member] | Cash equivalents and investments [Member] | Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value	9,063,000		9,724,000
Other assets [Member]
Investment in privately held Companies [Abstract]
Investments in privately-held companies	9,100,000		8,300,000
Certificates of deposit [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	3,314,000		678,000
Fair value, in loss position greater than twelve months	200,000
Fair value, total in loss position	3,514,000		678,000
Gross unrealized loss, in loss position less than twelve months	(3,000)		(3,000)
Gross unrealized loss, in loss position greater than twelve months	(1,000)
Gross unrealized loss, total in loss position	(4,000)		(3,000)
US Treasury and agency securities [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months			1,199,000
Fair value, total in loss position			1,199,000
Gross unrealized loss, in loss position less than twelve months			(1,000)
Gross unrealized loss, total in loss position			(1,000)
Corporate bonds [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	2,725,000		8,221,000
Fair value, in loss position greater than twelve months	1,517,000
Fair value, total in loss position	4,242,000		8,221,000
Gross unrealized loss, in loss position less than twelve months	(17,000)		(137,000)
Gross unrealized loss, in loss position greater than twelve months	(17,000)
Gross unrealized loss, total in loss position	(34,000)		(137,000)
Investments (Available for sale) [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	15,963,000		14,620,000
Gross Unrealized Gain	19,000		7,000
Gross Unrealized (Loss)	(38,000)		(141,000)
Fair Value	15,944,000		14,486,000
Investments (Available for sale) [Member] | Certificates of deposit [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	6,878,000		3,561,000
Gross Unrealized Gain	7,000		5,000
Gross Unrealized (Loss)	(4,000)		(3,000)
Fair Value	6,881,000		3,563,000
Investments (Available for sale) [Member] | US Treasury and agency securities [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	0		1,200,000
Gross Unrealized Gain	0		0
Gross Unrealized (Loss)	0		(1,000)
Fair Value	0		1,199,000
Investments (Available for sale) [Member] | Corporate bonds [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	9,085,000		9,859,000
Gross Unrealized Gain	12,000		2,000
Gross Unrealized (Loss)	(34,000)		(137,000)
Fair Value	9,063,000		9,724,000
Cash [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	27,490,000		25,299,000
Gross Unrealized Gain	0		0
Gross Unrealized (Loss)	0		0
Fair Value	27,490,000		25,299,000
Cash equivalents [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	8,013,000		857,000
Gross Unrealized Gain	0		0
Gross Unrealized (Loss)	0		0
Fair Value	8,013,000		857,000
Cash equivalents [Member] | Money market fund [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	8,013,000		857,000
Gross Unrealized Gain	0		0
Gross Unrealized (Loss)	0		0
Fair Value	8,013,000		857,000
Total cash and cash equivalents [Member]
Cash, cash equivalents and investments [Abstract]
Amortized Cost	35,503,000		26,156,000
Gross Unrealized Gain	0		0
Gross Unrealized (Loss)	0		0
Fair Value	$ 35,503,000		$ 26,156,000