Condensed Consolidated Statements of Earnings - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 892.6	$ 638.9	$ 1,787.9	$ 1,233.7
Operating expenses:
Cost of revenues	707.8	464.5	1,425.7	903.1
Selling, general and administrative expenses	126.0	104.2	237.3	201.3
Total operating expenses	833.8	568.7	1,663.1	1,104.4
Operating income	58.8	70.2	124.9	129.3
Interest expense, net	10.6	6.4	21.0	12.7
Other non-operating expenses, net	2.5	2.4	6.7	3.6
Earnings before income taxes	45.7	61.3	97.2	113.0
Provision for income taxes	15.6	21.1	33.4	39.2
Net earnings	$ 30.1	$ 40.2	$ 63.8	$ 73.8
Basic earnings per share (in dollars per share)	$ 0.25	$ 0.34	$ 0.54	$ 0.62
Diluted earnings per share (in dollars per share)	$ 0.25	$ 0.33	$ 0.52	$ 0.61
Weighted-average shares outstanding:
Basic (in shares)	118.7	118.5	118.6	118.4
Diluted (in shares)	121.5	122.0	121.5	121.9
Dividends declared per common share (in dollars per share)	$ 0.33	$ 0.30	$ 0.66	$ 0.6