Employee Benefit Plans (Assets Measured at NAV) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Assets Category:
Fair Value	$ 179.7	$ 154.3
NAV [Member]
Assets Category:
Fair Value	$ 179.3	154.1
Commingled Pools / Collective Trusts [Member] | U.S. Equity [Member]
Assets Category:
Fair Value		$ 50.8
Redemption Frequency (if currently eligible)	Daily	Daily
Commingled Pools / Collective Trusts [Member] | International Equity [Member]
Assets Category:
Fair Value		$ 8.3
Redemption Frequency (if currently eligible)	Daily	Daily
Commingled Pools / Collective Trusts [Member] | Fixed Income [Member]
Assets Category:
Fair Value	$ 64.9	$ 54.6
Redemption Frequency (if currently eligible)	Daily	Daily
Balanced pension trusts [Member] | International Equity [Member]
Assets Category:
Fair Value		$ 4.8
Redemption Frequency (if currently eligible)	Daily	Daily
Balanced pension trusts [Member] | Fixed Income [Member]
Assets Category:
Fair Value	$ 14.1	$ 13.6
Redemption Frequency (if currently eligible)	Daily	Daily
Pension Funds [Member] | Fixed Income [Member]
Assets Category:
Fair Value		$ 22.0
Redemption Frequency (if currently eligible)	Daily	Daily
Pension Fund Member | Fixed Income [Member]
Assets Category:
Fair Value	$ 25.2	$ 22.0
Fair Value, Inputs, Level 2 [Member]
Assets Category:
Fair Value	179.3	154.1
Fair Value, Inputs, Level 2 [Member] | Commingled Pools / Collective Trusts [Member] | Fixed Income [Member]
Assets Category:
Fair Value	64.9	54.6
Fair Value, Inputs, Level 2 [Member] | Balanced pension trusts [Member] | Fixed Income [Member]
Assets Category:
Fair Value	14.1	13.6
Fair Value, Inputs, Level 2 [Member] | Pension Fund Member | Fixed Income [Member]
Assets Category:
Fair Value	$ 25.2	$ 22.0