Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Security	Dec. 31, 2012 Security	Jan. 18, 2013	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	$ 15,700	$ 0	$ 15,900	$ 0
Auction rate securities	2,208	3,240
Duration of securities subject to temporary impairment, minimum (in months)	12 months
Amount of temporary impairment	192	260
Summarize the amortized cost basis, the aggregate fair value and gross unrealized holding [Abstract]
Amortized Cost Basis	2,400	3,500
Fair Value	2,208	3,240
Gross Unrealized Holding, Gains	0	0
Gross Unrealized Holding, Losses	(192)	(260)
Gross Unrealized Holding Gains (Losses), Net	(192)	(260)
Continuous unrealized loss position, Unrealized Losses [Abstract]
Number of securities with gross unrealized loss position	1	2
Weighted average duration of unrealized losses	70 months	58 months
Contingent consideration liability	15,700	0	15,900	0
Maximum [Member]
Continuous unrealized loss position, Unrealized Losses [Abstract]
Severity of the unrealized losses below amortized cost (in hundredths)	8.00%	8.00%
Maturities Greater Than Ten Years [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of temporary impairment	192	200
Summarize the amortized cost basis, the aggregate fair value and gross unrealized holding [Abstract]
Amortized Cost Basis	2,400	2,500
Fair Value	2,208	2,300
Gross Unrealized Holding, Gains	0	0
Gross Unrealized Holding, Losses	(192)	(200)
Gross Unrealized Holding Gains (Losses), Net	(192)	(200)
Investments Without Stated Maturity Dates [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of temporary impairment		60
Summarize the amortized cost basis, the aggregate fair value and gross unrealized holding [Abstract]
Amortized Cost Basis		1,000
Fair Value		940
Gross Unrealized Holding, Gains		0
Gross Unrealized Holding, Losses		(60)
Gross Unrealized Holding Gains (Losses), Net		(60)
U.S. Government Subsidized Securities [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of US government subsidized securities (in years)	10 years
U.S. Government Subsidized Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Auction rate securities	2,208
Auction Rate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Auction rate securities	2,208	3,240
Continuous unrealized loss position, Fair Value [Abstract]
Less than 12 Months, Fair Value	0	0
12 Months or Greater, Fair Value	2,208	3,240
Total, Fair Value	2,208	3,240
Continuous unrealized loss position, Unrealized Losses [Abstract]
Less than 12 Months, Unrealized Losses	0	0
12 Months or Greater, Unrealized Losses	(192)	(260)
Total, Unrealized Losses	(192)	(260)
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	15,700
Money market funds	60,364	56,224
Auction rate securities	2,208	3,240
Liability, total	15,700
Asset, total	62,572	59,464
Continuous unrealized loss position, Unrealized Losses [Abstract]
Contingent consideration liability	15,700
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	0
Money market funds	60,364	56,224
Auction rate securities	0	0
Liability, total	0
Asset, total	60,364	56,224
Continuous unrealized loss position, Unrealized Losses [Abstract]
Contingent consideration liability	0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	0
Money market funds	0	0
Auction rate securities	0	0
Liability, total	0
Asset, total	0	0
Continuous unrealized loss position, Unrealized Losses [Abstract]
Contingent consideration liability	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	15,700
Money market funds	0	0
Auction rate securities	2,208	3,240
Liability, total	15,700
Asset, total	2,208	3,240
Continuous unrealized loss position, Unrealized Losses [Abstract]
Contingent consideration liability	$ 15,700