Stock-Based Compensation	6 Months Ended
Stock-Based Compensation	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION In January 2017, our Board, upon the recommendation of its Compensation Committee, discontinued the AutoNation, Inc. 2008 Employee Equity and Incentive Plan and approved the AutoNation, Inc. 2017 Employee Equity and Incentive Plan (the “2017 Plan”), in each case subject to stockholder approval of the 2017 Plan at our 2017 Annual Meeting of Stockholders (the “2017 Annual Meeting”). The 2017 Plan provides for the grant of time-based and performance-based RSUs and restricted stock, stock options, stock appreciation rights, and other stock-based and cash-based awards to employees. A maximum of 5.5 million shares may be issued under the 2017 Plan. In January 2017, our Board’s Compensation Committee approved the 2017 annual equity awards for eligible employees under the 2017 Plan, which awards were issued on March 1, 2017, subject to stockholder approval of the 2017 Plan. Our stockholders approved the 2017 Plan at the 2017 Annual Meeting held on April 19, 2017, and on that date, the 2017 annual equity awards were considered granted for accounting purposes. The 2017 annual equity awards include time-based and performance-based RSUs. Time-based RSUs vest in equal installments over four years. The performance-based RSUs are subject to a one-year earnings performance measure. Certain performance-based RSUs vest in equal installments over four years, and others cliff vest after three years subject to the achievement of certain additional performance goals measured over a three-year period. The additional performance goals are based on an additional measure of earnings, a measure of return on invested capital, and a measure of our performance relative to certain customer satisfaction indices. We granted 0.6 million RSUs during the six months ended June 30, 2017, which were primarily related to the 2017 annual equity awards discussed above. The fair value of each RSU award grant is based on the closing price of our common stock on the date of grant. Compensation cost for time-based RSUs is recognized on a straight-line basis over the shorter of the stated vesting period or the period until employees become retirement-eligible, and for performance-based awards, is recognized over the requisite service period based on the current expectation that performance goals will be achieved at the stated target level. The amount of compensation cost recognized on performance-based RSUs depends on the relative satisfaction of the performance condition based on performance to date.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.