Pension Plans (Other Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Actual return on pension plan assets	(7.20%)
Maximize return	43.80%
Liquidity	56.20%
Defined contribution, maximum contribution limit	5.00%
Defined contribution plan, employer contributions	$ 13.1	$ 12.6	$ 11.9
Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.50%	7.50%
Managers’ securities holdings percentage maximum limit of total market value	7.50%