Significant Accounting Policies (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reserve for Possible Credit Losses
Days past due for income recognition on debt and preferred equity investments to be suspended	90 days
Loan loss reserves and charge offs	$ 0	$ 0	$ 564,000
Recoveries recorded	0	0	2,436,000
Income taxes
Federal, state and local tax provision	7,800,000	4,400,000	0
Debt and Preferred Equity Investments Held to Maturity
Reserve for Possible Credit Losses
Loan loss reserves and charge offs			$ 3,000,000