Cash, Cash Equivalents and Investments (Contractual Maturities) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Amortized Cost Basis
Due within one year	$ 1,363
Due after 1 year through 5 years	3,511
Due after 5 years through 10 years	107
Due after 10 years	224
Short-term investments, cost or amortized cost	5,205	$ 5,005
Aggregate Fair Value
Due within one year	1,363
Due after 1 year through 5 years	3,512
Due after 5 years through 10 years	107
Due after 10 years	223
Short-term investments, aggregate fair value	$ 5,205	$ 5,004