Acquired Lease Intangibles (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of above and below Market Leases	$ 17,078	$ 13,847	$ 9,890
Amortization of acquired in place leases	$ 14,400	$ 15,600	$ 13,200