Loans sales and securitizations (Details Textuals) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Loans sales and securitizations (Textuals) [Abstract]
Total servicing income on sold automobile loans	$ 300,000	$ 500,000	$ 1,000,000	$ 2,100,000
Total of automobile loans transferred in a securitization transaction	1,000,000,000		1,000,000,000
Gain or loss from sale of automobile loans in securitizations	15,500,000
Net proceeds received in securitization transaction	1,000,000,000
Residential Mortgage [Member]
Loans sales and securitizations (Textuals) [Abstract]
Total servicing fees included in mortgage banking income	$ 12,100,000	$ 12,100,000	$ 37,100,000	$ 36,600,000