Employee Benefit Plans - Stock Purchase Plan (Details) - Employee Stock [Member] - Employee Stock Purchase Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee benefit plans [Line Items]
Proceeds from purchase of shares by employees	$ 1.2	$ 1.0	$ 0.9
Number of shares issued by the Company	39,532	33,666	39,055
Recorded in share-based compensation, net of deferral	$ 0.3	$ 0.3	$ 0.2