Financial Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	$ 5,736,000	$ 95,000
Available-for-sale Securities, Gross Unrealized Losses	(70,000)	(246,000)
Short-term investments	140,958,000	65,222,000
Long-term investments	704,758,000	74,033,000
Cash and Available for Sale Securities, Amortized Cost Basis	3,716,677,000	3,511,339,000
Cash and Cash Equivalents, Fair Value Disclosure	3,722,343,000	3,511,188,000
Cash and cash equivalents	2,876,627,000	3,371,933,000	2,765,196,000	1,546,672,000
Payments to Acquire Equity Method Investments	4,500,000
Debt Maturities, Adjusted Cost:
Due in one year or less	188,431,000
Due after one year through five years	699,148,000
Total adjusted cost	887,579,000
Debt Maturities, Estimated Fair Value:
Due in one year or less	188,487,000
Due after one year through five years	704,758,000
Total fair value	893,245,000
Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	5,231,000	0
Available-for-sale Securities, Gross Unrealized Losses	(3,000)	0
Short-term investments	22,493,000	8,199,000
Long-term investments	513,929,000	0
Available-for-sale Securities, Fair Value Disclosure	3,309,845,000	3,208,660,000
Available-for-sale Securities	2,773,423,000	3,200,461,000
Debt Maturities, Adjusted Cost:
Total adjusted cost	3,304,617,000	3,208,660,000
Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	505,000	95,000
Available-for-sale Securities, Gross Unrealized Losses	(67,000)	(246,000)
Short-term investments	118,465,000	57,023,000
Long-term investments	190,829,000	74,033,000
Available-for-sale Securities, Fair Value Disclosure	323,304,000	137,406,000
Available-for-sale Securities	14,010,000	6,350,000
Debt Maturities, Adjusted Cost:
Total adjusted cost	322,866,000	137,557,000
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash, Amortized Cost Basis	89,194,000	165,122,000
Available-for-sale Securities, Gross Unrealized Gains	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Cash, Fair Value Disclosure	89,194,000	165,122,000
Short-term investments	0	0
Long-term investments	0	0
Money market funds [Member] | Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Short-term investments	0	0
Long-term investments	0	0
Available-for-sale Securities, Fair Value Disclosure	2,739,904,000	3,189,462,000
Available-for-sale Securities	2,739,904,000	3,189,462,000
Debt Maturities, Adjusted Cost:
Total adjusted cost	2,739,904,000	3,189,462,000
U.S. treasury securities [Member] | Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	5,231,000	0
Available-for-sale Securities, Gross Unrealized Losses	(3,000)	0
Short-term investments	22,493,000	6,199,000
Long-term investments	513,929,000	0
Available-for-sale Securities, Fair Value Disclosure	569,941,000	6,199,000
Available-for-sale Securities	33,519,000	0
Debt Maturities, Adjusted Cost:
Total adjusted cost	564,713,000	6,199,000
U.S. agency securities [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	58,000	11,000
Available-for-sale Securities, Gross Unrealized Losses	(1,000)	(7,000)
Short-term investments	53,438,000	25,890,000
Long-term investments	51,622,000	14,531,000
Available-for-sale Securities, Fair Value Disclosure	116,859,000	41,171,000
Available-for-sale Securities	11,799,000	750,000
Debt Maturities, Adjusted Cost:
Total adjusted cost	116,802,000	41,167,000
Non-U.S. government securities [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	10,000	0
Available-for-sale Securities, Gross Unrealized Losses	(2,000)	(8,000)
Short-term investments	2,730,000	8,213,000
Long-term investments	8,922,000	0
Available-for-sale Securities, Fair Value Disclosure	11,652,000	8,213,000
Available-for-sale Securities	0	0
Debt Maturities, Adjusted Cost:
Total adjusted cost	11,644,000	8,221,000
Municipal bond [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	1,000	0
Available-for-sale Securities, Gross Unrealized Losses	0	(1,000)
Short-term investments	752,000	0
Long-term investments	621,000	753,000
Available-for-sale Securities, Fair Value Disclosure	1,373,000	753,000
Available-for-sale Securities	0	0
Debt Maturities, Adjusted Cost:
Total adjusted cost	1,372,000	754,000
Corporate securities [Member] | Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains		0
Available-for-sale Securities, Gross Unrealized Losses		0
Short-term investments		2,000,000
Long-term investments		0
Available-for-sale Securities, Fair Value Disclosure		12,999,000
Available-for-sale Securities		10,999,000
Debt Maturities, Adjusted Cost:
Total adjusted cost		12,999,000
Corporate securities [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	436,000	84,000
Available-for-sale Securities, Gross Unrealized Losses	(64,000)	(230,000)
Short-term investments	61,545,000	22,920,000
Long-term investments	129,664,000	58,749,000
Available-for-sale Securities, Fair Value Disclosure	193,420,000	87,269,000
Available-for-sale Securities	2,211,000	5,600,000
Debt Maturities, Adjusted Cost:
Total adjusted cost	$ 193,048,000	$ 87,415,000