Leases - Operating Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) shopping_center	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Operating Leased Assets [Line Items]
Number of shopping centers with land leases | shopping_center	6
Ground lease expense	$ 2.5	$ 1.7	$ 1.8
Rent expense capitalized	0.9	0.9	0.8
Rent expense	$ 0.9	$ 1.4	$ 1.5
Minimum [Member]
Operating Leased Assets [Line Items]
Period of lease term	25 years
Maximum [Member]
Operating Leased Assets [Line Items]
Period of lease term	71 years