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
 3 Months Ended 9 Months Ended
Jun. 30, 2013
Sep. 30, 2013
item
Dec. 31, 2012
Sep. 30, 2012
Dec. 31, 2011
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   $ 230,882 $ 298,241    
Cash and cash equivalents   16,031 33,484 26,801 18,633
Available-for-sale securities   214,851 264,757    
Cash equivalents and available-for-sale securities          
Amortized Cost   216,222 273,972    
Gross Unrealized Gains   137 135    
Gross Unrealized Losses   (8) (53)    
Fair Value   216,351 274,054    
Years to Maturity          
Within One Year   183,088      
After One Year Through Two Years   33,263      
Weighted-average time to maturity of cash equivalents and available-for-sale securities   218 days      
Stated maturity period may be greater than this period and classified as current   1 year      
Proceeds from sale of available-for-sale securities 16,500 16,479      
Investments in unrealized loss position for more than twelve months   0 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   14      
Fair Value   31,263      
Unrealized Losses   (8)      
Money market funds
          
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   14,437 23,936    
U. S. treasury bills
          
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   2,104      
Cash equivalents and available-for-sale securities          
Amortized Cost   2,102      
Gross Unrealized Gains   2      
Fair Value   2,104      
Years to Maturity          
After One Year Through Two Years   2,104      
Government-sponsored enterprise securities
          
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   80,867 77,047    
Cash equivalents and available-for-sale securities          
Amortized Cost   80,809 77,041    
Gross Unrealized Gains   60 37    
Gross Unrealized Losses   (2) (31)    
Fair Value   80,867 77,047    
Years to Maturity          
Within One Year   53,203      
After One Year Through Two Years   27,664      
Fair value and gross unrealized losses of investments in individual securities in unrealized loss position          
Fair Value   2,998      
Unrealized Losses   (2)      
Corporate bonds and commercial paper
          
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   133,380 197,007    
Cash equivalents and available-for-sale securities          
Amortized Cost   133,311 196,931    
Gross Unrealized Gains   75 98    
Gross Unrealized Losses   (6) (22)    
Fair Value   133,380 197,007    
Years to Maturity          
Within One Year   129,885      
After One Year Through Two Years   3,495      
Fair value and gross unrealized losses of investments in individual securities in unrealized loss position          
Fair Value   28,265      
Unrealized Losses   (6)      
Checking account
          
Cash, cash equivalents and available-for-sale securities          
Cash, cash equivalents and available-for-sale securities   $ 94 $ 251