Notes Payable - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Total interest incurred	$ 74,929	$ 65,182	$ 44,332
Interest capitalized	(14,324)	(11,219)	(4,902)
Total interest expense	$ 60,605	$ 53,963	$ 39,430