Retirement Plans - Schedule of Components of Net Periodic Benefit Cost (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 5	$ 4
Interest cost	2	1	1
Expected return on plan assets	(2)	(2)	(2)
Net periodic benefit cost	$ 4	$ 5	$ 4