Equity - Restricted Stock (Details) - Restricted stock - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 13, 2020	Jan. 08, 2020	Jan. 07, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years	4 years
Shares
Unvested at beginning of period (in shares)						193,045	190,462	190,462
Granted (in shares)						75,419		110,830
Vested (in shares)				0	0	(78,010)	(78,431)	(101,109)
Forfeited (in shares)						(1,376)		(7,138)
Unvested at end of period (in shares)				189,078		189,078		193,045
Fair value of restricted stock per share at grant date	$ 32.64	$ 31.49	$ 24.85			$ 31.60
Stock Repurchased and Retired During Period, Shares						33,119		28,504
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value				$ 27.77		$ 27.77			$ 24.38
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value						23.11
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value						$ 26.15
Unrecognized compensation costs				$ 3,700		$ 3,700
Unrecognized compensation costs, period for recognition						2 years 6 months
Vested (in shares)				0	0	(78,010)	(78,431)	(101,109)
Fair value of shares vested				$ 0	$ 0	$ 2,463	$ 1,951