Borrowings and Subordinated Debentures (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Notes Payable, Other Payables
Debt Instrument [Line Items]
Debt Instruments Weighted Average Remaining Maturity Period	2 years 3 months
Unsecured Debt
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 80,000,000
Unused lines of Credit
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0	$ 0
American Financial Exchange
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0
Federal Home Loan Bank of San Francisco | Unsecured Debt
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	99,000,000
Line of Credit Facility, Amount Outstanding	0
Federal Reserve Bank Advances
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	2,100,000,000
Line of Credit Facility, Amount Outstanding	0	0
Loans Pledged as Collateral	3,000,000,000
Federal Home Loan Bank Advances | Secured Debt
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	2,300,000,000
Line of Credit Facility, Amount Outstanding	$ 550,000,000	$ 618,000,000