Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Effective tax rate attributable to CarGurus, Inc	27.70%	26.30%	21.80%
Change in valuation allowance	$ 29,000	$ 71,000
Deferred tax assets, federal net operating loss carryforwards	821,000
Deferred tax assets, state net operating loss carryforwards	$ 4,051,000
Percentage of annual limitation of taxable income	80.00%
Liabilities for uncertain tax positions	$ 598,000	$ 0
Federal
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 673,000
State
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration year	2040
Tax credit carryforwards	$ 322,000
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Tax credit carryforward limitations on use, cumulative ownership change, period	3 years
Tax credit carryforward, limitations on use	an ownership change, as defined by Section 382, results from transactions that increase the ownership of 5% stockholders in the stock of a corporation by more than 50% in the aggregate over a three-year period.
Open tax year	2018
Internal Revenue Service (IRS) | Maximum
Income Tax Disclosure [Line Items]
Tax credit carryforward limitations on use, cumulative ownership change percentage	50.00%
Revenue Commissioners, Ireland | Foreign
Income Tax Disclosure [Line Items]
Open tax year	2016