Notes Payable (Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Total interest incurred	$ 44,332	$ 42,767	$ 31,347
Interest capitalized	(4,902)	(9,243)	(4,697)
Total interest expense	$ 39,430	$ 33,524	$ 26,650