SCHEDULE IV - MORTGAGE LOANS ON REAL ESTATE - Reconciliation of Loans on Real Estate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at beginning of year	$ 147,188	$ 102,286	$ 126,656
Additions	171,794	48,500	31,169
Disposition of air rights through issuance of notes	0	29,539	0
Amortization and accretion	0	0	556
Repayments	(42,819)	(15,984)	(18,095)
Conversion to real estate through receipt of deed or through foreclosure	0	(13,386)	(38,000)
Other	0	(3,767)	0
Balance at end of year	$ 276,163	$ 147,188	$ 102,286