Interest Expense Interest Expense (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest expense	$ 20,431,000	$ 21,884,000	$ 43,308,000	$ 45,559,000
Amortization of deferred financing costs	714,000	1,241,000	1,878,000	2,458,000
Net unrealized loss (gain) on derivative financial instruments not designated as cash flow hedges	0	(432,000)	48,000	(1,551,000)
Capitalized interest	(8,038,000)	(4,666,000)	(14,953,000)	(9,182,000)
Interest Expense	$ 13,107,000	$ 18,027,000	$ 30,281,000	$ 37,284,000