Retirement Plans and Post Retirement Benefits Level 3 Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019
Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Fair value of plan assets, beginning of year balance	$ 275	$ 266
Fair value of plan assets, end of year balance	275	266	$ 294
Multi-strategy Funds
Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Fair value of plan assets, beginning of year balance	53
Fair value of plan assets, end of year balance	53		53
Significant Unobservable Inputs (Level 3)
Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Fair value of plan assets, beginning of year balance	0
Fair value of plan assets, end of year balance	0		0
Significant Unobservable Inputs (Level 3) | Multi-strategy Funds
Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Fair value of plan assets, beginning of year balance	0
Fair value of plan assets, end of year balance	0		0
Net Asset Value, previously Level 3 [Member] | Multi-strategy Funds
Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Fair value of plan assets, beginning of year balance	13	13
Total unrealized gains (losses)		0
Defined Benefit Plan, Redemptions	(13)	0
Defined Benefit Plan, Mangement Fees		0
Fair value of plan assets, end of year balance	$ 13	$ 13	$ 0