Note 3 - Available-for-Sale Investments (Details) - Summary of Fair Value of Available-for-Sale Investments - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
US Government Agencies Debt Securities [Member]
Bonds, notes and other securities:
Amortized cost	$ 100	$ 759
Fair value	100	759
Total Short-Term Investments [Member]
Bonds, notes and other securities:
Amortized cost	100	759
Fair value	100	759
Asset-backed Securities [Member]
Bonds, notes and other securities:
Amortized cost	37	42
Fair value	33	38
Total Long-Term Investments [Member]
Bonds, notes and other securities:
Amortized cost	37	42
Fair value	$ 33	$ 38