Goodwill and Other Intangible Assets (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) Reporting_Unit	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Indefinite-lived Intangible Assets [Line Items]
Reporting units for goodwill impairment testing (in reporting units) | Reporting_Unit	3
Goodwill	$ 3,306,000,000.0	$ 3,325,500,000	$ 3,370,000,000.0
Impairment loss	0	0	0
Total intangible amortization expense	90,000,000	$ 91,000,000	$ 82,000,000
Future amortization expense, year one	83,000,000
Future amortization expense, year two	78,000,000
Future amortization expense, year three	77,000,000
Future amortization expense, year four	73,000,000
Future amortization expense, year five	$ 66,000,000