Investments and Fair Value Measurements (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Cash, cash equivalents and investments [Abstract]
Cash	$ 21,638,000	$ 24,852,000
Cash Equivalents, at Carrying Value [Abstract]
Money market funds	1,122,000	109,000
Cash Equivalents, at Carrying Value, Total	22,760,000	24,961,000	25,792,000	30,634,000
Amortized Cost	44,904,000	45,682,000
Gross Unrealized Gain	1,913,000	1,933,000
Gross Unrealized (Loss)	(4,000)	(10,000)
Fair Value	46,813,000	47,605,000
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	20,464,000	10,569,000
Due after 1 through 5 years	1,680,000	10,152,000
Investments, amortized cost	22,144,000	20,721,000
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	22,375,000	12,499,000
Due after 1 through 5 years	1,678,000	10,145,000
Investments, fair value	24,053,000	22,644,000
Gain on sale of available for sale security	800,000
Unrealized gain, net of tax	1,600,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	1,918,000	7,898,000
Gross unrealized loss, in loss position less than twelve months	(1,000)	(9,000)
Fair value, in loss position greater than twelve months	3,621,000	4,431,000
Gross unrealized loss, in loss position greater than twelve months	(3,000)	(1,000)
Fair value, total in loss position	5,539,000	12,329,000
Gross unrealized loss, total in loss position	(4,000)	(10,000)
Minority Investments [Abstract]
Minority investments in unconsolidated privately-held companies	200,000	200,000
Recurring [Member]
Assets [Abstract]
Assets, fair value	25,175,000	22,753,000
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Assets, fair value	3,147,000	2,157,000
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Assets, fair value	22,028,000	20,596,000
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] | Money market fund - cash [Member]
Assets [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1,122,000	109,000
Recurring [Member] | Money market fund - cash [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1,122,000	109,000
Recurring [Member] | Money market fund - cash [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Recurring [Member] | Certificates of deposit [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	7,863,000	6,318,000
Recurring [Member] | Certificates of deposit [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0	0
Recurring [Member] | Certificates of deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	7,863,000	6,318,000
Recurring [Member] | Corporate bonds [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	14,165,000	14,278,000
Recurring [Member] | Corporate bonds [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0	0
Recurring [Member] | Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	14,165,000	14,278,000
Recurring [Member] | Corporate equity security [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	2,025,000	2,048,000
Recurring [Member] | Corporate equity security [Member] | Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	2,025,000	2,048,000
Recurring [Member] | Corporate equity security [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0	0
Other assets [Member]
Minority Investments [Abstract]
Investments in privately-held companies	11,000,000	10,900,000
Minority investments in unconsolidated privately-held companies	200,000	200,000
Certificates of deposit [Member]
Cash Equivalents, at Carrying Value [Abstract]
Amortized Cost	7,864,000	6,320,000
Gross Unrealized Gain	1,000	2,000
Gross Unrealized (Loss)	(2,000)	(4,000)
Fair Value	7,863,000	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	1,918,000	3,425,000
Gross unrealized loss, in loss position less than twelve months	(1,000)	(4,000)
Fair value, in loss position greater than twelve months	1,239,000	720,000
Gross unrealized loss, in loss position greater than twelve months	(1,000)	0
Fair value, total in loss position	3,157,000	4,145,000
Gross unrealized loss, total in loss position	(2,000)	(4,000)
Corporate bonds [Member]
Cash Equivalents, at Carrying Value [Abstract]
Amortized Cost	14,155,000	14,276,000
Gross Unrealized Gain	12,000	8,000
Gross Unrealized (Loss)	(2,000)	(6,000)
Fair Value	14,165,000	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	0	4,473,000
Gross unrealized loss, in loss position less than twelve months	0	(5,000)
Fair value, in loss position greater than twelve months	2,382,000	3,711,000
Gross unrealized loss, in loss position greater than twelve months	(2,000)	(1,000)
Fair value, total in loss position	2,382,000	8,184,000
Gross unrealized loss, total in loss position	(2,000)	(6,000)
Corporate equity security [Member]
Cash Equivalents, at Carrying Value [Abstract]
Amortized Cost	125,000	125,000
Gross Unrealized Gain	1,900,000	1,923,000
Gross Unrealized (Loss)	0	0
Fair Value	2,025,000	2,048,000
Total Investments [Member]
Cash Equivalents, at Carrying Value [Abstract]
Amortized Cost	22,144,000	20,721,000
Gross Unrealized Gain	1,913,000	1,933,000
Gross Unrealized (Loss)	(4,000)	(10,000)
Fair Value	$ 24,053,000	$ 22,644,000