Borrowings and Subordinated Debentures (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Non‑recourse debt
Debt Instrument [Line Items]
Debt Instruments Weighted Average Remaining Maturity Period	2 years 1 month
FHLB unsecured overnight advance
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 overnight borrowing
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	40,000,000.0	0
Federal Home Loan Bank of San Francisco | FHLB unsecured overnight advance
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	99,000,000
Line of Credit Facility, Amount Outstanding	90,000,000	0
Federal Reserve Bank Advances
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	1,800,000,000
Line of Credit Facility, Amount Outstanding	0	0
Loans Pledged as Collateral	3,000,000,000
Federal Home Loan Bank Advances | FHLB secured overnight advance
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	2,000,000,000
Line of Credit Facility, Amount Outstanding	787,000,000	618,000,000
Federal Home Loan Bank Advances | FHLB unsecured overnight advance
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 90,000,000	$ 0