Property, net - Assets Measured on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	$ 38,000	$ 86,100	$ 49,700
(Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	0	0	0
(Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	38,000	0	6,200
(Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	$ 0	$ 86,100	$ 43,500