Selected Quarterly Financial Data (Unaudited) - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effect of Fourth Quarter Events [Line Items]
Litigation Settlement, Amount		$ 42
Litigation Settlement, Expense, per share impact		$ 0.02
Impairment of Long-Lived Assets Held-for-use		$ 12
Impairment Effect on Earnings Per Share, after Tax		$ 0.01
Business Acquisition, Transaction Costs	$ 14				$ 4	$ 6	$ 8
Business Combination, Acquisition Related Costs, per share impact	$ 0.01
Tax Adjustments, Settlements, and Unusual Provisions	$ 39
Tax Adjustments, Settlements, and Unusual Provisions, per share impact	$ 0.02
Research and Development tax credit, amount	$ 61		$ 62
Research and Development tax credit, per share impact	$ 0.03		$ 0.03
Gain on strategic investment, net of tax			$ 33	$ 45
Gain on strategic investment, net of tax, per diluted share			$ 0.02	$ 0.02
Impairment of strategic investment				$ 24	$ 0	$ 33	$ 0
Other Than Temporary Impairment Losses, Investments, per share impact				$ 0.01