Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Other operating	$ 7,992	$ 7,759	$ 9,750
Parking Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	6,930	6,611	6,121
Property Lease Guaranty Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	675	726	3,058
Management Fee Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	273	308	402
Miscellaneous [Member]
Disaggregation of Revenue [Line Items]
Other operating	$ 114	$ 114	$ 169