Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Jul. 24, 2017
Senior Notes | Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (percent)	5.25%		5.25%
Carrying value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	$ 762,334	$ 676,880
Carrying value | Senior Notes | Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	300,000	300,000
Carrying value | Real Estate Mortgages and Other Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	462,334	376,880
Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	754,871	698,087
Fair value | Senior Notes | Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	288,000	312,750
Fair value | Real Estate Mortgages and Other Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	$ 466,871	$ 385,337