v2.4.0.6
Short-term Investments Investments Classified by Contractual Maturity Date (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost $ 299,946 $ 374,688
Unrealized Gain in Accumulated OCI 32 180
Unrealized Loss in Accumulated OCI 6 6
Aggregate Fair Value 299,972 374,862
Equity Securities
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 7 7
Unrealized Gain in Accumulated OCI 0 0
Unrealized Loss in Accumulated OCI 6 6
Aggregate Fair Value 1 1
US Treasury Securities
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 299,939 374,681
Unrealized Gain in Accumulated OCI 32 180
Unrealized Loss in Accumulated OCI 0 0
Aggregate Fair Value $ 299,971 $ 374,861