Leases - Operating Leases (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) shopping_center	Mar. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Number of shopping centers with land leases | shopping_center	6
Ground lease expense	$ 0.8	$ 0.6
Rent expense capitalized	0.1	0.2
Rent expense	$ 0.2	$ 0.1
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