Schedule IV - Mortgage Loans on Real Estate Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance as of the beginning of the year	$ 0	$ 28,520	$ 20,000
Additions:
New mortgage loans	0	11,924	8,520
Deductions:
Mortgage loan included in the consideration for the acquisition of a building	0	(11,924)	0
Collection of mortgage loans	0	(28,520)	0
Balance as of the end of the year	$ 0	$ 0	$ 28,520