Fair Value of Financial Instruments (Schedule) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Minimum | Assumed Mortgage Notes Payable
Fair Value of Financial Instruments (Details) [Line Items]
Interest rate (in percentage)	4.00%
Maximum | Assumed Mortgage Notes Payable
Fair Value of Financial Instruments (Details) [Line Items]
Interest rate (in percentage)	5.00%
Weighted Average | Assumed Mortgage Notes Payable
Fair Value of Financial Instruments (Details) [Line Items]
Interest rate (in percentage)	4.20%
Significant Other Observable Inputs (Level 2) | Senior Notes Due 2024
Fair Value of Financial Instruments (Details) [Line Items]
Long-term debt, fair value	$ 248.3
Significant Other Observable Inputs (Level 2) | Senior Notes Due 2023
Fair Value of Financial Instruments (Details) [Line Items]
Long-term debt, fair value	259.6
Significant Unobservable Inputs (Level 3) | Assumed Mortgage Notes Payable
Fair Value of Financial Instruments (Details) [Line Items]
Notes payable, fair value	72.7
Significant Unobservable Inputs (Level 3) | Originated Mortgage Notes Payable
Fair Value of Financial Instruments (Details) [Line Items]
Notes payable, fair value	$ 33.2
Interest rate (in percentage)	4.60%
Significant Unobservable Inputs (Level 3) | Senior Notes Due 2027
Fair Value of Financial Instruments (Details) [Line Items]
Long-term debt, fair value	$ 249.5
Significant Unobservable Inputs (Level 3) | Senior Notes Due 2026
Fair Value of Financial Instruments (Details) [Line Items]
Long-term debt, fair value	$ 196.2