Employee Benefit Plans, Restricted Stock Plan (Details) - Restricted Stock [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Deferred Compensation Arrangements [Abstract]
Number of shares authorized (in shares)	150,000		150,000
Number of shares available for grant (in shares)	130,452		130,452
Unvested Shares [Roll Forward]
Outstanding, beginning of period (in shares)	10,764		9,764
Granted (in shares)	0		5,130
Forfeited (in shares)	0		(152)
Vested (in shares)	0		(3,978)
Outstanding, end of period (in shares)	10,764		10,764
Weighted Average Market Price [Roll Forward]
Outstanding, beginning of period (in dollars per share)	$ 60.16		$ 58.21
Granted (in dollars per share)	0		60.21
Forfeited (in dollars per share)	0		60.00
Vested (in dollars per share)	0		(55.46)
Outstanding, end of period (in dollars per share)	$ 60.16		$ 60.16
Additional General Disclosures [Abstract]
Share-based compensation expense	$ 78	$ 68	$ 219	$ 187
Compensation cost related to nonvested awards that has not yet been recognized	$ 648		$ 648
Period over which compensation cost is expected to be recognized			3 years