Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Adjustment of deferred tax balances	$ 36	$ 3	$ 23
Domestic production activities deduction	12		14
Federal research and development credits	6	5	5
Deferred Tax Assets, Valuation Allowance	271	177
Tax reserve adjustment			11
Non-deductible transaction costs			$ 2
Effect of expiration of statute of limitations during next twelve months	8
Gross tax liability for tax positions that may not be sustained under a more likely than not threshold	17
Additional interest recognized on tax liability	1
Accrued interest on tax liability	1	1
Deferred Tax Assets, Net, Current	55	$ 50
Proceeds from Income Tax Refunds	120
Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Amount	13
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Amount	19
Federal net operating loss carryforward	6,700
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Federal net operating loss carryforward	$ 1,000