Fair Value Measurements and Derivatives Instruments - Summary of Effects on Consolidated Financial Statements of Designated As Cash Flow Hedges (Details) - Interest Rate Swaps - Cash Flow Hedges - Designated - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments Gain Loss [Line Items]
(Loss) income recognized in Other comprehensive income	$ (1,917)	$ 4,210	$ (6,075)	$ 7,080
Interest Expense
Derivative Instruments Gain Loss [Line Items]
Net loss reclassified from Accumulated other comprehensive loss into Interest expense	$ (2,597)	$ (2,221)	$ (3,433)	$ (4,831)