Supplemental Detail for Certain Components of Consolidated Balance Sheets - Distributions Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Distributions payable
Declared distributions	$ 50,344	$ 43,675
Noncontrolling interests
Distributions payable
Declared distributions	124	150
Common stock
Distributions payable
Declared distributions	47,963	41,268
Preferred stock
Distributions payable
Declared distributions	$ 2,257	$ 2,257