Derivatives - Narrative (Details) - Interest rate contract - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2017	Sep. 30, 2017
Derivative [Line Items]
Term of derivative contract	3 years
Notional amount of derivative	$ 60,000,000.0
Derivative fixed interest rate (as a percent)	1.58%
Derivative quarterly reduction amount		$ 5,000,000.0