Consolidated Statements of Operating Income (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 488.2	$ 410.9
Operating costs:
Cost of revenues	391.3	332.8
Selling, general, and administrative expenses	51.8	40.8
Costs and Expenses, Total	443.1	373.6
Total operating profit	45.1	37.3
Interest expense	3.3	1.9
Other, net (income) expense	(0.2)	(0.2)
Income before income taxes	42.0	35.6
Provision (benefit) for income taxes	10.4	7.9
Net income	$ 31.6	$ 27.7
Net income per common share:
Basic (in dollars per share)	$ 0.65	$ 0.57
Diluted (in dollars per share)	$ 0.65	$ 0.56
Weighted average number of shares outstanding
Basic (in shares)	47.8	47.9
Diluted (in shares)	48.4	48.5
Dividends declared per common share	$ 0.05	$ 0.05