Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	$ 499.6	$ 478.7	$ 994.2	$ 925.0
Expenses:
Cost of revenues	235.9	230.6	483.2	433.9
Selling, general and administrative expenses	115.6	115.1	223.5	206.2
Restructuring expenses	0.0	3.7	0.0	19.5
Total expenses	351.5	349.4	706.7	659.6
Operating earnings	148.1	129.3	287.5	265.4
Interest expense	(36.4)	(34.3)	(74.1)	(66.5)
Other income, net	1.3	1.6	3.6	4.2
Earnings before income taxes	113.0	96.6	217.0	203.1
Provision for income taxes	(43.2)	(24.0)	(68.8)	(54.0)
Net earnings from continuing operations	69.8	72.6	148.2	149.1
Net earnings (loss) from discontinued operations	(45.7)	18.3	(40.0)	34.1
Net earnings	24.1	90.9	108.2	183.2
Less: net earnings attributable to noncontrolling interest	1.8	1.9	3.9	3.9
Net earnings attributable to CDK	$ 22.3	$ 89.0	$ 104.3	$ 179.3
Net earnings (loss) attributable to CDK per share - basic:
Continuing operations (in dollars per share)	$ 0.56	$ 0.56	$ 1.19	$ 1.13
Discontinued operations (in dollars per share)	(0.38)	0.14	(0.33)	0.27
Total net earnings attributable to CDK per share - basic (in dollars per share)	0.18	0.70	0.86	1.40
Net earnings (loss) attributable to CDK per share - diluted:
Continuing operations (in dollars per share)	0.55	0.56	1.18	1.13
Discontinued operations (in dollars per share)	(0.37)	0.14	(0.33)	0.26
Total net earnings attributable to CDK per share - diluted (in dollars per share)	$ 0.18	$ 0.70	$ 0.85	$ 1.39
Weighted-average common shares outstanding:
Basic (shares)	121.6	126.8	121.5	128.2
Diluted (shares)	122.1	127.5	122.1	129.1