Common Stock Repurchases - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Common Stock Repurchases (Textual) [Abstract]
Repurchased shares	175,091
Common stock purchased for treasury	$ 9.1
Shares remain available for repurchase	265,449
Repurchase of common stock for employee tax withholding obligations amount, shares	21,767	26,916
Repurchase of common stock for employee tax withholding obligations amount	$ 1.2	$ 1.3