Investments in Qualified Affordable Housing Projects (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Jul. 01, 2017
Schedule of Equity Method Investments [Line Items]
Carrying value of qualified affordable housing project investments		$ 7,637,000	$ 6,331,000
Increase (decrease) in QAHP	$ (2,450,000)
Commitment	$ 0
Investment amortization		1,714,000	1,335,000
Tax credits and other benefits		(2,190,000)	(1,927,000)
Total		$ (476,000)	$ (592,000)
Metropolitan Bancgroup, Inc.
Schedule of Equity Method Investments [Line Items]
Carrying value of qualified affordable housing project investments				$ 5,481,000