Mortgage Notes Payable - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Disclosure [Abstract]
Interest expense capitalized	$ 3,751	$ 3,428	$ 12,752	$ 9,405
Fair value of mortgage notes payable	$ 4,088,227		$ 4,088,227		$ 4,250,816