Shareholders' Equity, Noncontrolling Interests and Other Comprehensive Income - Preferred OP Units (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2016 $ / shares shares	Dec. 31, 2017 USD ($) $ / Units shares	Dec. 31, 2016 shares	Dec. 31, 1999 shares
Class of Stock [Line Items]
Limited partners' capital account, units issued and converted (in shares)		81,453	351,250
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
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)		5,000
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)		3,328,873	3,308,875
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
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 convertible units of share price falls above $35.20 (in Shares)	2.8409
Minimum | Gotham Plaza | Preferred OP Units
Class of Stock [Line Items]
Share price at conversion date | $ / shares	$ 28.80
Maximum | Gotham Plaza | Preferred OP Units
Class of Stock [Line Items]
Share price at conversion date | $ / shares	$ 35.20