Summary of Significant Accounting Policies - Impact of New Guidance (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets	$ 12,083	$ 12,129	$ 10,876
Total liabilities	10,607	10,331
Total liabilities and stockholders’ equity	$ 12,083	12,129
Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		12,467
Total liabilities		10,669
Total liabilities and stockholders’ equity		12,467
Deferred tax current assets
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		0
Deferred tax current assets | Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		248
Deferred tax current assets | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred taxes, assets		(248)
Total current assets
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		1,298
Total current assets | Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		1,546
Total current assets | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred taxes, assets		(248)
Other long-term assets
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		7
Other long-term assets | Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total assets		97
Other long-term assets | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Simplifying the Presentation of Debt Issuance Costs		(90)
Assets | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Simplifying the Presentation of Debt Issuance Costs		(90)
Deferred taxes, assets		(248)
Long-term debt
New Accounting Pronouncement, Early Adoption [Line Items]
Total liabilities		7,344
Long-term debt | Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total liabilities		7,434
Long-term debt | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Simplifying the Presentation of Debt Issuance Costs		90
Deferred tax long-term liabilities
New Accounting Pronouncement, Early Adoption [Line Items]
Total liabilities		1,444
Deferred tax long-term liabilities | Previously reported
New Accounting Pronouncement, Early Adoption [Line Items]
Total liabilities		1,692
Deferred tax long-term liabilities | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred taxes, liabilities		(248)
Liabilities | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Simplifying the Presentation of Debt Issuance Costs		90
Deferred taxes, liabilities		(248)
Liabilities and stockholders' equity | New Accounting Pronouncement, early adoption effect
New Accounting Pronouncement, Early Adoption [Line Items]
Simplifying the Presentation of Debt Issuance Costs		90
Deferred taxes, liabilities		$ (248)