Quarterly report pursuant to Section 13 or 15(d)

Cash, Cash Equivalents and Available-For-Sale Securities (Details)

v2.4.0.8
Cash, Cash Equivalents and Available-For-Sale Securities (Details) (USD $)
In Thousands, unless otherwise specified
 6 Months Ended
Jun. 30, 2014
item
Dec. 31, 2013
Jun. 30, 2013
Dec. 31, 2012
Cash, cash equivalents and available-for-sale securities        
Cash, cash equivalents and available-for-sale securities $ 176,030 $ 211,975    
Cash and cash equivalents 23,882 20,854 21,868 33,484
Available-for-sale securities 152,148 191,121    
Cash equivalents and available-for-sale securities        
Amortized Cost 163,105 202,674    
Gross Unrealized Gains 54 64    
Gross Unrealized Losses (12) (17)    
Years to Maturity        
Within One Year 124,842      
After One Year Through Two Years 38,305      
Weighted-average time to maturity of cash equivalents and available-for-sale securities 214 days      
Stated maturity period may be greater than this period and classified as current 1 year      
Number of investments in continuous unrealized loss position for more than twelve months 0      
Fair value and gross unrealized losses of investments in individual securities in unrealized loss position        
Number of individual securities in unrealized loss position for twelve months or less 19      
Other-than-temporary impairments of securities 0      
Fair Value 36,422      
Unrealized Losses (12)      
US Treasury Securities [Member]
        
Cash equivalents and available-for-sale securities        
Amortized Cost 2,047 2,083    
Gross Unrealized Gains 2 2    
Years to Maturity        
Within One Year 2,049      
US Government-sponsored Enterprises Debt Securities [Member]
        
Cash equivalents and available-for-sale securities        
Amortized Cost 57,496 67,160    
Gross Unrealized Gains 22 29    
Gross Unrealized Losses (8) (11)    
Years to Maturity        
Within One Year 32,009      
After One Year Through Two Years 25,501      
Fair value and gross unrealized losses of investments in individual securities in unrealized loss position        
Fair Value 14,045      
Unrealized Losses (8)      
Corporate Bond Securities and Commercial Paper [Member]
        
Cash equivalents and available-for-sale securities        
Amortized Cost 103,562 133,431    
Gross Unrealized Gains 30 33    
Gross Unrealized Losses (4) (6)    
Years to Maturity        
Within One Year 90,784      
After One Year Through Two Years 12,804      
Fair value and gross unrealized losses of investments in individual securities in unrealized loss position        
Fair Value 22,377      
Unrealized Losses (4)      
Demand Deposits [Member]
        
Cash, cash equivalents and available-for-sale securities        
Cash, cash equivalents and available-for-sale securities 401 195    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value 12,482 9,059    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value 12,482 9,059    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value 163,147 202,721    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value 2,049 2,085    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value 57,510 67,178    
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bond Securities and Commercial Paper [Member]
        
Cash equivalents and available-for-sale securities        
Fair Value $ 103,588 $ 133,458