Interest Expense Interest Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest expense	$ 91,651,000	$ 69,178,000	$ 54,379,000
Amortization of deferred financing costs	4,661,000	3,011,000	1,478,000
Unrealized gain on interest rate swaps and caps	(926,000)	(1,348,000)	0
Derivative, Gain (Loss) on Derivative, Net	(135,000)	27,000	0
Capitalized interest	(20,804,000)	(12,727,000)	(4,076,000)
Interest Expense	$ 74,447,000	$ 58,141,000	$ 51,781,000