Favorable and Unfavorable Acquired Lease Contracts, net - Lease Contracts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 6.1	$ 7.2	$ 14.6
Weighted average life (years)	12 years 6 months
Favorable
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 5.7	$ 6.6	$ 8.3
Weighted average life (years)	12 years	14 years 1 month 6 days	11 years 10 months 24 days
Unfavorable
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 6.7	$ 8.8	$ 10.1
Weighted average life (years)	7 years 10 months 24 days	10 years 8 months 12 days	10 years 6 months