Plan Information (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Deferred Compensation Liability, Current and Noncurrent	$ 196.2	$ 213.2
Incentive compensation plan initiation year	2014
Number of shares initially available for grant	28.8
Maximum shares participants are eligible to receive	2.0
Maximum cash award per employee	$ 10.0
Number of years stock options expire from grant date	10 years
Vesting period in which the fair value of shares on grant date is amortized over, years	3 years
Minimum [Member]
Stock options exercisable period	2 years
Maximum [Member]
Stock options exercisable period	4 years