River Financial Corporation (Parent Company Only) Financial Information - Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Deferred income taxes	$ 1,977	$ 3,352
Other assets	3,701	3,245
Total assets	823,292	810,417
Liabilities
Note payable	5,357	6,428
Total liabilities	733,343	727,967
Common stock related to 401(k) Employee Stock Ownership Plan	950	623
Stockholders' Equity
Common stock	5,114	5,091
Additional paid in capital	64,935	64,656
Retained earnings	22,388	15,032
Accumulated other comprehensive loss	(2,116)	(2,153)
Treasury stock, at cost	(372)	(176)
Common stock related to 401(k) Employee Stock Ownership Plan	(950)	(623)
Total stockholders' equity	88,999	81,827	$ 74,614
Total equity	89,949	82,450
Total liabilities and stockholders' equity	823,292	810,417
River Financial Corporation
Assets
Cash	1,619	1,865
Investment in River Bank & Trust	93,593	86,880
Deferred income taxes	9	16
Other assets	91	117
Total assets	95,312	88,878
Liabilities
Note payable	5,357	6,428
Accrued expenses	6
Total liabilities	5,363	6,428
Common stock related to 401(k) Employee Stock Ownership Plan	950	623
Stockholders' Equity
Common stock	5,114	5,091
Additional paid in capital	64,935	64,656
Retained earnings	22,388	15,032
Accumulated other comprehensive loss	(2,116)	(2,153)
Treasury stock, at cost	(372)	(176)
Common stock related to 401(k) Employee Stock Ownership Plan	(950)	(623)
Total stockholders' equity	88,999	81,827
Total equity	89,949	82,450
Total liabilities and stockholders' equity	$ 95,312	$ 88,878