CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Repayment of Sellers' Floor Plan Notes Payable Dealership Acquisitions	$ 62.2	$ 60.3	$ 117.8
5.50% senior subordinated notes due 2026
Interest rate (as a percent)	5.50%
5.375% Senior Subordinated Notes Due 2024
Interest rate (as a percent)	5.375%	5.375%	5.375%