Derivatives - Loss Recorded in Accumulated Other Comprehensive Income (Loss) (Details) - Derivatives designated as hedging instrument - Cash flow hedges - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income	$ (2,185)	$ 129	$ (2,096)	$ 122
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income	$ (2,185)	$ 129	$ (2,096)	$ 122