Noncontrolling Interests - Schedule of Fund II Assets (Details)	12 Months Ended
	Dec. 31, 2015
Noncontrolling Interest [Line Items]
Ownership percentage	95.90%
Hayden Ferry Lakeside I
Noncontrolling Interest [Line Items]
Location	Phoenix, AZ
Ownership percentage	30.00%
Hayden Ferry Lakeside II
Noncontrolling Interest [Line Items]
Location	Phoenix, AZ
Ownership percentage	30.00%
Hayden Ferry Lakeside III
Noncontrolling Interest [Line Items]
Location	Phoenix, AZ
Ownership percentage	70.00%
Hayden Ferry Lakeside IV and adjacent garage
Noncontrolling Interest [Line Items]
Location	Phoenix, AZ
Ownership percentage	30.00%
3344 Peachtree
Noncontrolling Interest [Line Items]
Location	Atlanta, GA
Ownership percentage	33.00%
Two Liberty Place
Noncontrolling Interest [Line Items]
Location	Philadelphia, PA
Ownership percentage	19.00%