Recent Acquisition (Details) - USD ($) $ in Thousands			3 Months Ended	6 Months Ended
		Apr. 01, 2018	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Mar. 31, 2018
Valuation of the assets acquired and liabilities assumed [Abstract]
Goodwill				$ 28,300	$ 28,300
TCSB Bancorp, Inc. [Member]
Recent Acquisition [Abstract]
Equity interest issued to each holder of common stock under merger agreement (in shares)		1.1166
Total value of common stock and cash paid in lieu of fractional shares		$ 5
Equity issued under merger agreement (in shares)		2,710,000
Options issued under merger agreement (in shares)		190,000
Fair value of equity issued under merger agreement		$ 64,500
Valuation of the assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents						$ 23,521
Interest bearing deposits - time						4,054
Securities available for sale						6,066
Federal Home Loan Bank stock						778
Loans, net						295,799
Property and equipment, net						1,067
Capitalized mortgage loan servicing rights						3,047
Accrued income and other assets						3,362
Other intangibles	[1]					5,798
Total assets acquired						343,492
Deposits						287,710
Other borrowings						14,345
Subordinated debentures						3,768
Accrued expenses and other liabilities						1,429
Total liabilities assumed						307,252
Net assets acquired						36,240
Goodwill						28,300
Purchase price (fair value of consideration)						64,540
Decrease in goodwill			$ (700)
Fair value of acquired receivables						292,900
Gross contractual amounts receivable						$ 298,600
TCSB Bancorp, Inc. [Member] | Core Deposits [Member]
Valuation of the assets acquired and liabilities assumed [Abstract]
Estimated fair value of intangible assets		$ 5,800
Estimated useful life				10 years

[1] Relates to core deposit intangibles (see note #7).