Derivatives - Effect on Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, (Gain) Loss [Line Items]
Interest expense presented in the Statements of Operations in which the effects of cash flow hedges are recorded	$ 19,360	$ 17,363	$ 36,406	$ 34,793
Interest rate swaps | Cash flow hedges
Derivative Instruments, (Gain) Loss [Line Items]
Amount of loss recognized in other comprehensive income on derivative	2,301	6,215	30,954	9,601
Amount of loss (gain) reclassified from AOCI into income	2,995	(92)	4,066	(220)
Interest expense presented in the Statements of Operations in which the effects of cash flow hedges are recorded	$ 19,360	$ 17,363	$ 36,406	$ 34,793