Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended												3 Months Ended	6 Months Ended			3 Months Ended			6 Months Ended					3 Months Ended			6 Months Ended					3 Months Ended			6 Months Ended					3 Months Ended			6 Months Ended					3 Months Ended			6 Months Ended																																															3 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Gasoline swaps	Dec. 31, 2012 Gasoline swaps	Jun. 30, 2013 Interest rate caps	Dec. 31, 2012 Interest rate caps	Jun. 30, 2013 Foreign exchange forward contracts	Dec. 31, 2012 Foreign exchange forward contracts	Jun. 30, 2013 Foreign exchange options	Dec. 31, 2012 Foreign exchange options	Mar. 31, 2013 Level 2	Dec. 31, 2011 Level 2	Jun. 30, 2013 Level 3	Jun. 30, 2013 Level 3	Mar. 31, 2013 Level 3	Dec. 31, 2012 Level 3	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments	Dec. 31, 2012 Recurring Derivatives not designated as hedging instruments		Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Gasoline swaps		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Gasoline swaps	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Gasoline swaps		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Gasoline swaps	Dec. 31, 2012 Recurring Derivatives not designated as hedging instruments Gasoline swaps		Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Interest rate caps		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Interest rate caps	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Interest rate caps		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Interest rate caps	Dec. 31, 2012 Recurring Derivatives not designated as hedging instruments Interest rate caps		Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Foreign exchange forward contracts		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange forward contracts	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Foreign exchange forward contracts		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange forward contracts	Dec. 31, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange forward contracts		Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Foreign exchange options		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange options	Jun. 30, 2013 Recurring Derivatives not designated as hedging instruments Foreign exchange options		Jun. 30, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange options	Dec. 31, 2012 Recurring Derivatives not designated as hedging instruments Foreign exchange options		Jun. 30, 2013 Recurring Total Derivatives not designated as hedging instruments	Dec. 31, 2012 Recurring Total Derivatives not designated as hedging instruments	Jun. 30, 2013 Recurring Total Derivatives not designated as hedging instruments Gasoline swaps	Dec. 31, 2012 Recurring Total Derivatives not designated as hedging instruments Gasoline swaps	Jun. 30, 2013 Recurring Total Derivatives not designated as hedging instruments Interest rate caps	Dec. 31, 2012 Recurring Total Derivatives not designated as hedging instruments Interest rate caps	Jun. 30, 2013 Recurring Total Derivatives not designated as hedging instruments Foreign exchange forward contracts	Dec. 31, 2012 Recurring Total Derivatives not designated as hedging instruments Foreign exchange forward contracts	Jun. 30, 2013 Recurring Total Derivatives not designated as hedging instruments Foreign exchange options	Dec. 31, 2012 Recurring Total Derivatives not designated as hedging instruments Foreign exchange options	Jun. 30, 2013 Recurring Level 1 Derivatives not designated as hedging instruments	Dec. 31, 2012 Recurring Level 1 Derivatives not designated as hedging instruments	Jun. 30, 2013 Recurring Level 1 Derivatives not designated as hedging instruments Gasoline swaps	Dec. 31, 2012 Recurring Level 1 Derivatives not designated as hedging instruments Gasoline swaps	Jun. 30, 2013 Recurring Level 1 Derivatives not designated as hedging instruments Interest rate caps	Dec. 31, 2012 Recurring Level 1 Derivatives not designated as hedging instruments Interest rate caps	Jun. 30, 2013 Recurring Level 1 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Dec. 31, 2012 Recurring Level 1 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Jun. 30, 2013 Recurring Level 1 Derivatives not designated as hedging instruments Foreign exchange options	Dec. 31, 2012 Recurring Level 1 Derivatives not designated as hedging instruments Foreign exchange options	Mar. 31, 2013 Recurring Level 2	Dec. 31, 2011 Recurring Level 2	Jun. 30, 2013 Recurring Level 2 Derivatives not designated as hedging instruments	Dec. 31, 2012 Recurring Level 2 Derivatives not designated as hedging instruments	Jun. 30, 2013 Recurring Level 2 Derivatives not designated as hedging instruments Gasoline swaps	Dec. 31, 2012 Recurring Level 2 Derivatives not designated as hedging instruments Gasoline swaps	Jun. 30, 2013 Recurring Level 2 Derivatives not designated as hedging instruments Interest rate caps	Dec. 31, 2012 Recurring Level 2 Derivatives not designated as hedging instruments Interest rate caps	Jun. 30, 2013 Recurring Level 2 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Dec. 31, 2012 Recurring Level 2 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Jun. 30, 2013 Recurring Level 2 Derivatives not designated as hedging instruments Foreign exchange options	Dec. 31, 2012 Recurring Level 2 Derivatives not designated as hedging instruments Foreign exchange options	Jun. 30, 2013 Recurring Level 3 Derivatives not designated as hedging instruments	Dec. 31, 2012 Recurring Level 3 Derivatives not designated as hedging instruments	Jun. 30, 2013 Recurring Level 3 Derivatives not designated as hedging instruments Gasoline swaps	Dec. 31, 2012 Recurring Level 3 Derivatives not designated as hedging instruments Gasoline swaps	Jun. 30, 2013 Recurring Level 3 Derivatives not designated as hedging instruments Interest rate caps	Dec. 31, 2012 Recurring Level 3 Derivatives not designated as hedging instruments Interest rate caps	Jun. 30, 2013 Recurring Level 3 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Dec. 31, 2012 Recurring Level 3 Derivatives not designated as hedging instruments Foreign exchange forward contracts	Jun. 30, 2013 Recurring Level 3 Derivatives not designated as hedging instruments Foreign exchange options	Dec. 31, 2012 Recurring Level 3 Derivatives not designated as hedging instruments Foreign exchange options	Jun. 30, 2013 Dollar Thrifty Automotive Group Inc Level 3	Jun. 30, 2013 Dollar Thrifty Automotive Group Inc Level 3	Jun. 30, 2013 Minimum	Jun. 30, 2013 Maximum
Financial Instruments
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value															$ 0	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings													0	0
Available-for-sale Securities, Fair Value Disclosure													132.0	132.0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax													2.0	2.0																																																																																					0	5.1
Fair Value of Derivative Instruments
Asset Derivatives	5.5	4.5			0.6	0.9	4.8	3.4	0.1	0.2							5.5	[1],[2]		5.5	[1],[2]		4.5	[1],[2]	0	[1],[2]		0	[1],[2]		0	[1],[2]	0.6	[1],[2]		0.6	[1],[2]		0.9	[1],[2]	4.8	[1],[2]		4.8	[1],[2]		3.4	[1],[2]	0.1	[1],[2]		0.1	[1],[2]		0.2	[1],[2]	5.5	4.5			0.6	0.9	4.8	3.4	0.1	0.2	0	0			0	0	0	0	0	0			5.5	4.5			0.6	0.9	4.8	3.4	0.1	0.2	0	0			0	0	0	0	0	0
Liability Derivatives	3.4	5.5	0.9	0.1	0.6	0.9	1.9	4.5									3.4	[1],[2]		3.4	[1],[2]		5.5	[1],[2]	0.9	[1],[2]		0.9	[1],[2]		0.1	[1],[2]	0.6	[1],[2]		0.6	[1],[2]		0.9	[1],[2]	1.9	[1],[2]		1.9	[1],[2]		4.5	[1],[2]	0	[1],[2]		0	[1],[2]		0	[1],[2]	3.4	5.5	0.9	0.1	0.6	0.9	1.9	4.5			0	0	0	0	0	0	0	0					3.4	5.5	0.9	0.1	0.6	0.9	1.9	4.5			0	0	0	0	0	0	0	0
Amount of gain or loss recognized on derivative income																	(9.6)		(11.0)	(3.7)		(7.1)			(2.5)		(3.3)	(0.8)		(1.5)			0		(0.1)	0.1		(0.1)			(7.1)		(7.7)	(2.9)		(5.6)			0		0.1	(0.1)		0.1
Gross assets offset in Balance Sheet	0	0			0	0	0	0	0	0
Net recognized assets in Balance Sheet	5.5	4.5			0.6	0.9	4.8	3.4	0.1	0.2
Financial Instruments	2.8	1.5			0	0	2.8	1.3	0	0.2
Cash Collateral	0	0			0	0	0	0	0	0
Net Amount	2.7	3.0			0.6	0.9	2.0	2.1	0.1	0
Gross liabilities offset in Balance Sheet	0	0	0	0	0	0	0	0
Net recognized liabilities in Balance Sheet	3.4	5.5	0.9	0.1	0.6	0.9	1.9	4.5
Financial Instruments	2.8	1.5	0.9	0	0	0	1.9	1.5
Cash Collateral	0	0	0	0	0	0	0	0
Net Amount	0.6	4.0	0	0.1	0.6	0.9	0	3.0
Debt
Maximum initial maturity period of borrowings	90 days
Aggregate fair value of all debt											17,699.0	15,529.4
Aggregate carrying value of all debt																																																																													17,382.2	14,999.1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases													130.0	130.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements													$ 0	$ 0
Fair Value Inputs, Discount Rate																																																																																																					6.00%	21.00%
Fair Value Assumptions, Expected Volatility Rate																																																																																																					36.00%	42.00%

[1] All fair value measurements were primarily based upon significant observable (Level 2) inputs.

[2] All asset derivatives are recorded in "Prepaid expenses and other assets" and all liability derivatives are recorded in "Accrued liabilities" on our condensed consolidated balance sheets.