Earnings per Common Share - Operating Partnership Units (Details) - shares		6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Noncontrolling interest
Number of common shares issued for OP unit redeemed by a noncontrolling interest unit holder	1,171,494
Operating Partnership | Noncontrolling Interests
Noncontrolling interest
Units held by noncontrolling interest unit holders		1,150,827	2,349,561
Percentage of OP Units issued by the Operating Partnership	3.50%	3.50%	7.10%