Fair Value Measurement, Financial Assets Measured at Fair Value on Nonrecurring Basis (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Level 3 [Member]
Assets [Abstract]
Mortgage loans held for sale	$ 0
Level 1 [Member]
Assets [Abstract]
Mortgage loans held for sale	0
Level 2 [Member]
Assets [Abstract]
Mortgage loans held for sale	400,000
Fair Value on a Nonrecurring Basis [Member]
Assets [Abstract]
Mortgage loans held for sale	400,000
Impaired loans, net	5,885,000	$ 5,087,000
Other real estate owned, net	$ 1,356,000	1,356,000
Fair Value on a Nonrecurring Basis [Member] | Level 3 [Member]
Financial Assets Recorded on a Nonrecurring Basis [Abstract]
Minimum age of appraisal of real estate property for fair value to be considered Level 3	1 year
Assets [Abstract]
Mortgage loans held for sale	$ 0
Impaired loans, net	125,000	46,000
Other real estate owned, net	1,356,000	1,356,000
Fair Value on a Nonrecurring Basis [Member] | Level 1 [Member]
Assets [Abstract]
Mortgage loans held for sale	0
Impaired loans, net	0	0
Other real estate owned, net	0	0
Fair Value on a Nonrecurring Basis [Member] | Level 2 [Member]
Assets [Abstract]
Mortgage loans held for sale	400,000
Impaired loans, net	5,760,000	5,041,000
Other real estate owned, net	0	$ 0
Fair Value on a Nonrecurring Basis [Member] | Mortgage Loans Held for Sale [Member]
Financial Assets Recorded on a Nonrecurring Basis [Abstract]
Nonrecurring fair value adjustments	$ 0