Long-Term Debt - Components Of Net Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Disclosure [Abstract]
Interest expense	$ 7,694	$ 8,171	$ 23,635	$ 24,511
Interest income	(652)	(994)	(2,085)	(2,263)
Capitalized interest	(5,141)	(3,928)	(15,346)	(11,504)
Net interest expense	$ 1,901	$ 3,249	$ 6,204	$ 10,744