Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest Expense
Interest expense before capitalized interest	$ 16,800	$ 17,921	$ 33,466	$ 34,478
Amortization of deferred financing costs	1,045	779	2,092	1,398
Interest expense related to finance lease right-of-use assets	428	418	854	562
Net unrealized (gaim) loss on derivative financial instruments not designated as cash flow hedges	46	17	(87)	(30)
Capitalized interest	(1,546)	(3,365)	(3,256)	(8,633)
Interest expense	$ 16,773	$ 15,770	$ 33,069	$ 27,775