Fair Value Hierarchy For Financial Assets And Liabilities Measured At Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	$ 10,580,000
Convertible debt	(2,938,101)
Foreign exchange derivative assets	47,311
Foreign exchange derivative liabilities	(23,426)
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,441,347
Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,719,470
US Government Agencies Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,043,816
US Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,373,186
High Yield Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	498,617
Asset-backed Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	3,235
Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,027,517
Auction Rate Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	74,846
Foreign Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,252,990
Publicly Traded Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	144,976
Strategic Investments Held At Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	254,338
Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative liabilities	(1,502)
Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	5,430,017
Fair Value, Inputs, Level 1 | Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,441,347
Fair Value, Inputs, Level 1 | Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,715,470
Fair Value, Inputs, Level 1 | US Government Agencies Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,128,224
Fair Value, Inputs, Level 1 | Publicly Traded Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	144,976
Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	5,075,137
Convertible debt	(2,938,101)
Foreign exchange derivative assets	47,311
Foreign exchange derivative liabilities	(23,426)
Fair Value, Inputs, Level 2 | Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	4,000
Fair Value, Inputs, Level 2 | US Government Agencies Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	915,592
Fair Value, Inputs, Level 2 | US Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,373,186
Fair Value, Inputs, Level 2 | High Yield Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	498,617
Fair Value, Inputs, Level 2 | Asset-backed Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	3,235
Fair Value, Inputs, Level 2 | Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,027,517
Fair Value, Inputs, Level 2 | Foreign Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,252,990
Fair Value, Inputs, Level 2 | Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative liabilities	(1,502)
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	74,846
Fair Value, Inputs, Level 3 | Auction Rate Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	74,846
Fair Value, Inputs, Level 3 | Strategic Investments Held At Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	$ 254,338