Share Repurchase Plan (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of treasury stock by class

The following table summarizes the remaining authorized repurchase amount under the program as at December 31, 2018.

(millions)	December 31, 2018
Total authorized repurchase amount	$	30.0
Total value of shares repurchased	7.5
Total remaining authorized repurchase amount	$	22.5