Earnings per Share - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 21, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Antidilutive securities excluded from diluted earnings per share calculation (in shares)		481,000	274,000	412,000	191,000
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock issued (in shares)	2,702,500
Net proceeds from issuance of common stock	$ 55,700,000			$ 0	$ 55,641,000
CapGen Capital Group III LP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock issued (in shares)	6,210,000
Net proceeds from issuance of common stock	$ 0