Acquired Lease Intangibles (Details) - Intangible Assets and Liabilities - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Assets acquired in place	$ 82,778	$ 79,205
Acquired lease intangible assets, net	82,778	79,205
Liabilities:
Below-market leases	222,929	190,321
Accumulated amortization	(43,945)	(35,363)
Acquired lease intangible liabilities, net	178,984	154,958
In-place leases
Assets:
Assets acquired in place	99,924	93,952
Accumulated amortization	(36,971)	(33,034)
Above-market leases
Assets:
Assets acquired in place	33,176	30,251
Accumulated amortization	$ (13,351)	$ (11,964)