Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Unearned Employee Stock Ownership Plan Shares	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2016	$ 204,780	$ 192	$ 173,047	$ 39,483	$ (8,318)	$ 376
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,004	0	0	9,004	0	0
Other comprehensive loss, net of tax effect	(66)	0	0	0	0	(66)
Net exercise of stock options (198,026 shares)	(1,237)	2	(1,239)
Prepayment of ESOP Share Acquisition Loan	1,125	(8)	(7,185)		8,318
Repurchase and retirement of common stock	(10,819)	(7)	(10,812)	0	0	0
Cash dividends declared on common stock	(5,153)	0	0	(5,153)	0	0
Ending Balance at Dec. 31, 2017	197,634	179	153,811	43,274	0	370
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	19,342	0	0	19,342	0	0
Other comprehensive loss, net of tax effect	(99)	0	0	0	0	(99)
Prepayment of ESOP Share Acquisition Loan	0
Nonvested stock awards-stock-based compensation expense	6	0	6	0	0	0
Repurchase and retirement of common stock	(23,284)	(14)	(23,270)	0	0	0
Cash dividends declared on common stock	(6,449)	0	0	(6,449)	0	0
Ending Balance at Dec. 31, 2018	$ 187,150	$ 165	$ 130,547	$ 56,167	$ 0	$ 271