Retirement Plans (Schedule of Valuation of the Company's Pension Plan Assets by Pricing Categories) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 308	$ 289
(Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	240	227
(Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30	31
(Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38	31
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	6
Cash and cash equivalents | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	6
Cash and cash equivalents | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	100	89
Equity securities | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83	67
Equity securities | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17	22
Equity securities | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	127	135
Corporate debt securities | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	127	135
Corporate debt securities | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate debt securities | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74	59
Other | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	19
Other | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	9
Other | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 38	$ 31