Shareholders' Equity, Noncontrolling Interests and Other Comprehensive Income - Preferred OP Units (Details)	6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) $ / Units shares	Jun. 30, 2016 $ / shares shares	Dec. 31, 2016 shares	Dec. 31, 1999 shares
Class of Stock [Line Items]
Limited partners' capital account, units issued and converted (in shares)	41,166		303,536
Units converted from Series A Preferred OP Units (in shares)	185,600
Denominator for Series A Preferred OP Unit conversion | $	$ 7.50
Preferred OP Units [Member]
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)	0
Series C Preferred OP Units
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)	1,250
Series A Preferred Stock
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)				1,580
Preferred stock, stated value per unit | $ / Units	1,000
Per unit conversion amount, Series A Preferred OP Units (in dollars per unit) | $ / Units	22.50
Per unit conversion annual rate, Preferred OP Units	9.00%
Limited partners' capital account, units issued and converted (in shares)	1,392
Common Shares
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)			4,830,000
Operating Partnership, as General Partner or Managing Member
Class of Stock [Line Items]
Preferred OP Units (in shares)	3,361,397	3,317,760
Operating Partnership, as General Partner or Managing Member | Series A Preferred Stock
Class of Stock [Line Items]
Preferred OP Units (in shares)	188	188
Gotham Plaza | Preferred OP Units [Member]
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)		141,593
Gotham Plaza | Common Shares
Class of Stock [Line Items]
Issuance of common shares, net of issuance costs (in Shares)		442,478
Share price (in dollars per share) | $ / shares		$ 100.00
Preferred quarterly distribution per share price | $ / shares		$ 0.9375
Number of convertible units if share price falls below $28.80 (in shares)		3.4722
Number of convertiable units of share price falls above $35.20 (in Shares)		2.8409
Minimum | Gotham Plaza | Preferred OP Units [Member]
Class of Stock [Line Items]
Share price at conversion date | $ / shares		$ 28.80
Maximum | Gotham Plaza | Preferred OP Units [Member]
Class of Stock [Line Items]
Share price at conversion date | $ / shares		$ 35.20