Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

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Fair Value Measurements (Details) (USD $)
 1 Months Ended 12 Months Ended
Feb. 29, 2008
Jun. 30, 2010
Dec. 31, 2011
Jun. 30, 2011
Fair Value Measurements [Abstract]        
Cash excluded from fair value measurement     $ 192,400,000 $ 165,900,000
Time deposits excluded from fair value measurement     73,193,000 [1] 65,402,000 [1]
Auction Rate Securities, Contractual Maturity Date (in years), Low   20    
Auction Rate Securities, Contractual Maturity Date (in years), High   30    
Auction Failure in Par Value 48,200,000      
Auction Rate Securities, Sold at Par   16,800,000    
Total
        
Fair Value Measurements        
Marketable securities     1,911,051,000 [2] 1,807,277,000 [3]
Derivative assets     789,000 1,970,000
Executive Deferred Savings Plan        
EDSP money market and other     3,467,000 1,806,000
EDSP mutual funds     118,556,000 126,227,000
Executive Deferred Savings Plan total     122,023,000 128,033,000
Total Financial Assets     2,033,863,000 [2] 1,937,280,000 [3]
Derivative liabilities     (2,329,000) (2,127,000)
Total Financial Liabilities     (2,329,000) (2,127,000)
Total | Money market and other
        
Fair Value Measurements        
Cash Equivalents     591,032,000 481,770,000
Total | U.S. Treasury securities
        
Fair Value Measurements        
Cash Equivalents       4,400,000
Marketable securities     71,302,000 54,496,000
Total | U.S. Government agency securities
        
Fair Value Measurements        
Cash Equivalents       6,010,000
Marketable securities     449,356,000 314,173,000
Total | Municipal securities
        
Fair Value Measurements        
Marketable securities     41,473,000 38,957,000
Total | Corporate debt securities
        
Fair Value Measurements        
Cash Equivalents     5,000,000 21,982,000
Marketable securities     716,707,000 853,403,000
Total | Sovereign securities
        
Fair Value Measurements        
Marketable securities     36,181,000 32,086,000
Level 1
        
Fair Value Measurements        
Marketable securities     1,126,133,000 [2] 869,045,000 [3]
Derivative assets     0 0
Executive Deferred Savings Plan        
EDSP money market and other     3,467,000 1,806,000
EDSP mutual funds     93,895,000 95,971,000
Executive Deferred Savings Plan total     97,362,000 97,777,000
Total Financial Assets     1,223,495,000 [2] 966,822,000 [3]
Derivative liabilities     0 0
Total Financial Liabilities     0 0
Level 1 | Money market and other
        
Fair Value Measurements        
Cash Equivalents     591,032,000 481,770,000
Level 1 | U.S. Treasury securities
        
Fair Value Measurements        
Cash Equivalents       0
Marketable securities     67,302,000 52,396,000
Level 1 | U.S. Government agency securities
        
Fair Value Measurements        
Cash Equivalents       6,010,000
Marketable securities     449,356,000 314,173,000
Level 1 | Municipal securities
        
Fair Value Measurements        
Marketable securities     0 0
Level 1 | Corporate debt securities
        
Fair Value Measurements        
Cash Equivalents     0 0
Marketable securities     0 0
Level 1 | Sovereign securities
        
Fair Value Measurements        
Marketable securities     18,443,000 14,696,000
Level 2
        
Fair Value Measurements        
Marketable securities     784,918,000 [2] 938,232,000 [3]
Derivative assets     789,000 1,970,000
Executive Deferred Savings Plan        
EDSP money market and other     0 0
EDSP mutual funds     24,661,000 30,256,000
Executive Deferred Savings Plan total     24,661,000 30,256,000
Total Financial Assets     810,368,000 [2] 970,458,000 [3]
Derivative liabilities     (2,329,000) (2,127,000)
Total Financial Liabilities     (2,329,000) (2,127,000)
Level 2 | Money market and other
        
Fair Value Measurements        
Cash Equivalents     0 0
Level 2 | U.S. Treasury securities
        
Fair Value Measurements        
Cash Equivalents       4,400,000
Marketable securities     4,000,000 2,100,000
Level 2 | U.S. Government agency securities
        
Fair Value Measurements        
Cash Equivalents       0
Marketable securities     0 0
Level 2 | Municipal securities
        
Fair Value Measurements        
Marketable securities     41,473,000 38,957,000
Level 2 | Corporate debt securities
        
Fair Value Measurements        
Cash Equivalents     5,000,000 21,982,000
Marketable securities     716,707,000 853,403,000
Level 2 | Sovereign securities
        
Fair Value Measurements        
Marketable securities     $ 17,738,000 $ 17,390,000
[1] Time deposits excluded from fair value measurements.
[2] Excludes cash of $192.4 million held in operating accounts and time deposits of $73.2 million as of December 31, 2011.
[3] Excludes cash of $165.9 million held in operating accounts and time deposits of $65.4 million as of June 30, 2011.