Employee Stock Ownership Plan - Loan, Expense and Shares (Details) - USD ($)		3 Months Ended
	Jan. 01, 2009	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Employee Stock Ownership Plan
Allocated shares		479,040		466,807
Unearned shares		428,164		440,397
Total ESOP shares		907,204		907,204
Fair value of unearned shares, in thousands		$ 10,511,000		$ 13,626,000
ESOP
Employee Stock Ownership Plan
Amount borrowed from employer	$ 9,800,000
Shares purchased	978,650
Percentage of shares issued in initial public offering	8.00%
Employee stock ownership plan, price per share of shares acquired in initial public offering (in dollars per share)	$ 10.00
Term of loan		20 years
ESOP expense		$ 339,000	$ 334,000
ESOP | Prime rate
Employee Stock Ownership Plan
Variable interest rate		prime rate, as published in The Wall Street Journal