Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Stock-Based Compensation Expense

The table below shows the Company's stock-based compensation expense related to the restricted stock units for the three and six months ended June 30, 2018 and 2017, respectively, and is included in General and administrative expenses within the Condensed Consolidated Statements of Income:

	Three Months Ended				Six Months Ended
(millions) (unaudited)	June 30, 2018		June 30, 2017		June 30, 2018		June 30, 2017
Stock-based compensation expense	$	0.3	$	0.2	$	0.4	$	0.4

The table below shows the Company's stock-based compensation expense related to the Performance-Based Incentive Program for the three and six months ended June 30, 2018 and 2017, respectively, and is included in General and administrative expenses within the Condensed Consolidated Statements of Income:

	Three Months Ended				Six Months Ended
(millions) (unaudited)	June 30, 2018		June 30, 2017		June 30, 2018		June 30, 2017
Stock-based compensation expense	$	0.6	$	0.5	$	1.1	$	1.2