Segment Information (Details 1) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	2
Number of reportable segments | segment	2
Segment Information
Operating revenues	$ 645.5	$ 689.6
Operating expenses
Cost of services (exclusive of depreciation and amortization)	394.6	393.9
Selling, general and administrative	162.4	175.2
Depreciation and amortization	47.7	44.3
Total operating expenses	604.7	613.4
Operating profit (loss)	40.8	76.2
Interest expense	38.0	56.5
Other (income) expense, net	(2.0)	(2.1)
Intercompany expense (income)	0.0	0.0
Income (loss) from continuing operations before income taxes	4.8	21.8
Income taxes	2.0	6.5
Net income (loss) from continuing operations	2.8	15.3
Total assets	5,999.7	6,301.6	$ 6,581.2
Operating Segments | ADESA Auctions
Segment Information
ADESA Auction Services	567.0	599.7
Operating expenses
Cost of services (exclusive of depreciation and amortization)	370.7	370.7
Selling, general and administrative	122.8	126.6
Depreciation and amortization	39.1	35.0
Total operating expenses	532.6	532.3
Operating profit (loss)	34.4	67.4
Interest expense	0.8	0.7
Other (income) expense, net	0.0	(1.9)
Intercompany expense (income)	0.7	10.3
Income (loss) from continuing operations before income taxes	32.9	58.3
Income taxes	8.8	15.9
Net income (loss) from continuing operations	24.1	42.4
Total assets	3,279.5	3,797.0
Operating Segments | AFC
Segment Information
AFC	78.5	89.9
Operating expenses
Cost of services (exclusive of depreciation and amortization)	23.9	23.2
Selling, general and administrative	6.5	7.2
Depreciation and amortization	2.7	2.4
Total operating expenses	33.1	32.8
Operating profit (loss)	45.4	57.1
Interest expense	13.6	17.1
Other (income) expense, net	(0.1)	(0.1)
Intercompany expense (income)	(0.8)	(1.2)
Income (loss) from continuing operations before income taxes	32.7	41.3
Income taxes	8.1	10.8
Net income (loss) from continuing operations	24.6	30.5
Total assets	2,445.3	2,406.1
Holding Company
Segment Information
Operating revenues	0.0	0.0
Operating expenses
Cost of services (exclusive of depreciation and amortization)	0.0	0.0
Selling, general and administrative	33.1	41.4
Depreciation and amortization	5.9	6.9
Total operating expenses	39.0	48.3
Operating profit (loss)	(39.0)	(48.3)
Interest expense	23.6	38.7
Other (income) expense, net	(1.9)	(0.1)
Intercompany expense (income)	0.1	(9.1)
Income (loss) from continuing operations before income taxes	(60.8)	(77.8)
Income taxes	(14.9)	(20.2)
Net income (loss) from continuing operations	(45.9)	(57.6)
Total assets	$ 274.9	$ 98.5