Business combinations and divestitures (Assets Acquired Liabilities Assumed) (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 01, 2011 Donlen Corporation	Nov. 19, 2012 Dollar Thrifty
Acquisition
Cash and cash equivalents				$ 35,600,000	$ 535,000,000
Restricted cash and cash equivalents					307,000,000
Receivables				64,000,000	170,000,000
Inventories					8,000,000
Prepaid expenses and other assets				7,000,000	41,000,000
Revenue earning equipment				1,120,600,000	1,614,000,000
Property and equipment				13,500,000	119,000,000
Other intangible assets				75,000,000	1,546,000,000
Other assets					35,000,000
Goodwill	1,341,872,000	392,094,000	328,600,000	51,100,000	885,000,000
Accounts payable				(39,300,000)	(43,000,000)
Accrued liabilities				(226,800,000)	(277,000,000)
Deferred taxes on income				(121,900,000)	(864,000,000)
Debt				728,800,000	1,484,000,000
Total				$ 250,000,000	$ 2,592,000,000