Summary of Significant Accounting Policies (Redeemable Noncontrolling Interest in Consolidated Joint Venture) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accounting Policies [Abstract]
Net income allocated to noncontrolling interest	$ 33	$ 32	$ 67	$ 66
Payments to Noncontrolling Interests			134	$ 142
Noncontrolling interest	$ 2,300		$ 2,300		$ 2,400