2007
Schedule of Available-for-sale Securities [Line Items]Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]Marketable Securities, CurrentUS Government-sponsored Enterprises Debt Securities [Member]260,000,000
Asset-backed Securities [Member]186,000,000
Other Debt Securities [Member]133,000,000
Major Types of Debt and Equity Securities [Domain]579,000,000
Marketable Securities, NoncurrentUS Government-sponsored Enterprises Debt Securities [Member]56,000,000
Asset-backed Securities [Member]267,000,000
Auction Rate Securities [Member]16,000,000
Other Debt Securities [Member]29,000,000
Corporate Medium-Term Notes Securities [Member]112,000,000
Major Types of Debt and Equity Securities [Domain]480,000,000
Marketable SecuritiesMajor Types of Debt and Equity Securities [Domain]1,059,000,000