Related Party Transactions - Transactions (Details)		3 Months Ended								12 Months Ended
	Nov. 19, 2025 USD ($) franchise	Dec. 31, 2025 USD ($) member $ / shares	Sep. 30, 2025 USD ($) $ / shares	Jun. 30, 2025 USD ($) $ / shares	Mar. 31, 2025 USD ($) $ / shares	Dec. 31, 2024 USD ($) $ / shares	Sep. 30, 2024 USD ($) $ / shares	Jun. 30, 2024 USD ($) $ / shares	Mar. 31, 2024 USD ($) $ / shares	Dec. 31, 2025 USD ($) member $ / shares	Dec. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares
Related party transactions
Revenues		$ 7,769,200,000	$ 8,053,000,000	$ 8,032,500,000	$ 7,953,800,000	$ 8,077,600,000	$ 7,929,500,000	$ 8,065,000,000	$ 7,792,700,000	$ 31,808,500,000	$ 31,864,800,000	$ 30,916,500,000
Operating lease liability		2,563,000,000								2,563,000,000
Proceeds from sale of property and equipment										27,500,000	26,200,000	30,700,000
Number of retail automotive franchised dealerships acquired | franchise	4
Equity method investment, distribution										98,700,000	99,100,000	169,900,000
Outstanding debt		2,165,500,000				1,852,000,000				2,165,500,000	1,852,000,000
Gross profit		1,243,800,000	1,299,600,000	1,352,200,000	1,321,400,000	1,313,100,000	1,293,500,000	1,316,200,000	1,294,300,000	5,217,000,000	5,217,100,000	5,147,400,000
Net income		$ 186,700,000	$ 225,300,000	$ 267,500,000	$ 258,400,000	$ 250,200,000	$ 239,100,000	$ 256,500,000	$ 227,600,000	$ 937,900,000	$ 973,400,000	$ 1,114,200,000
Net income attributable to Penske Automotive Group common stockholders (in dollars per share) | $ / shares		$ 2.83	$ 3.41	$ 4.03	$ 3.86	$ 3.73	$ 3.57	$ 3.81	$ 3.38	$ 14.13	$ 14.49	$ 16.31
Net income attributable to Penske Automotive Group common stockholders (in dollars per share) | $ / shares		$ 2.83	$ 3.41	$ 4.03	$ 3.86					$ 14.13	$ 14.49	$ 16.31
Change in Reporting Entity, Adjustment | Affiliated Entity
Related party transactions
Revenues										$ 1,450,000,000	$ 1,410,000,000	$ 1,390,000,000
Gross profit										208,700,000	203,600,000	213,500,000
Net income										$ 48,300,000	$ 50,000,000.0	$ 55,600,000
Net income attributable to Penske Automotive Group common stockholders (in dollars per share) | $ / shares										$ 0.73	$ 0.75	$ 0.81
Net income attributable to Penske Automotive Group common stockholders (in dollars per share) | $ / shares										$ 0.73	$ 0.75	$ 0.81
Penske Truck Leasing Co LP
Related party transactions
Ownership percentage		28.90%								28.90%
Penske Corporation | Penske Truck Leasing Co LP
Related party transactions
Ownership interest in Penske Truck Leasing Company										41.10%
Mitsui and Co | Penske Truck Leasing Co LP
Related party transactions
Ownership interest in Penske Truck Leasing Company										30.00%
Related Party
Related party transactions
Other expenses										$ 6,800,000	$ 6,000,000.0	$ 5,300,000
Revenues										1,300,000	1,400,000	1,300,000
Receivables		$ 52,000				$ 51,000				52,000	51,000
Payables		900,000				600,000				900,000	600,000
Rent expense on leases										7,900,000	7,200,000	6,700,000
Operating lease liability		61,100,000				$ 67,400,000				61,100,000	67,400,000
Proceeds from sale of property and equipment										16,000,000.0
Consideration transferred	$ 519,446,253
Net worth	47,696,253
Payment to acquire entity under common control	363,619,353
Related Party | Promissory Note | 4.50% Senior Subordinated Promissory Note
Related party transactions
Principal amount	$ 155,826,900
Interest rate	4.50%
Outstanding debt		$ 151,500,000								151,500,000
Debt instrument term	3 years
Interest expense										$ 800,000
Related Party | Individual Minority Owner | Penske Motor Group LLC
Related party transactions
Ownership interest in Penske Truck Leasing Company	5.00%
Corporate Joint Venture | Penske Truck Leasing Co LP
Related party transactions
Number of members on the advisory board | member										11
Number of members on the advisory committee the Company is entitled to | member		1								1
Pro rata quarterly distributions, percentage of net income		50.00%								50.00%
Partnership interest that my be transferred without complying with the right of first offer										9.02%
Equity method investment, distribution										$ 98,700,000	$ 98,400,000	$ 168,800,000
Corporate Joint Venture | Penske Truck Leasing Co LP
Related party transactions
Purchases of trucks and parts										36,000,000.0
Corporate Joint Venture | Premier Truck Group
Related party transactions
Purchases of trucks and parts										$ 1,300,000
Subsidiary of Common Parent | Penske Automotive Holdings Corp | Penske Motor Group LLC
Related party transactions
Ownership percentage	25.65%
Affiliated Entity | GWOOD 2 LLC | Penske Motor Group LLC
Related party transactions
Ownership interest in Penske Truck Leasing Company	69.35%
Immediate Family Member of Management or Principal Owner
Related party transactions
Common control transactions, ownership interest percentage	52.00%
Common control transactions, voting interest percentage	73.00%