Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 2) (Credit Risk)	3 Months Ended
	Mar. 31, 2013
Concentrations of credit risk
Number of states with largest concentration by loan type	5
Total loans outstanding | Noncovered loans | California
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	79.00%
Total loans outstanding | Noncovered loans | Nevada
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	2.00%
Total loans outstanding | Noncovered loans | New York
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	7.00%
Total loans outstanding | Noncovered loans | Other states
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	12.00%
Total loans outstanding | Covered loans | California
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	37.00%
Total loans outstanding | Covered loans | Nevada
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	7.00%
Total loans outstanding | Covered loans | New York
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	4.00%
Total loans outstanding | Covered loans | Texas
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	11.00%
Total loans outstanding | Covered loans | Ohio
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	5.00%
Total loans outstanding | Covered loans | Other states
Concentrations of credit risk
Percent of total loans outstanding (as a percent)	36.00%