Commitments and Contingent Liabilities (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Commitments and Contingent Liabilities
Lease period, minimum	5 years
Lease period, maximum	20 years
Loss Contingencies
Letters of credit outstanding	$ 24.1
Surety bonds posted	13.3
Holdings | Holdings Bond
Loss Contingencies
Senior unsecured notes issued	700.0
Senior subordinated convertible notes, interest rate (as a percent)	3.80%
Penske Truck Leasing Co., L.P.
Loss Contingencies
Ownership interest in Penske Truck Leasing Co (as a percent)	9.00%
Guarantee of Indebtedness of Others | GECC
Loss Contingencies
Percentage of interest agreed to indemnify if GECC required to make any payments of principal or interest	9.00%
Annual fee pay for acting as co-obligor	0.95
Value of interest payments included in maximum amount of Company's potential obligations	$ 63.1