Securities, Available-for-sale Securities (Details) $ in Thousands	Sep. 30, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 Months, Fair Value	$ 8,923	$ 10,119
12 Months or More, Fair Value	3,027
Total, Estimated Fair Value	11,950	10,119
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, Unrealized Losses	101	50
12 Months or More, Unrealized Losses	46
Total, Unrealized Losses	147	50
U.S. Treasury Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 Months, Fair Value	1,975
Total, Estimated Fair Value	1,975
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, Unrealized Losses	15
Total, Unrealized Losses	$ 15
AFS securities, Number of securities in continuous unrealized loss position | security	2
U.S. Government Agency Notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 Months, Fair Value	$ 6,948	10,119
12 Months or More, Fair Value	3,027
Total, Estimated Fair Value	9,975	10,119
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, Unrealized Losses	86	50
12 Months or More, Unrealized Losses	46
Total, Unrealized Losses	$ 132	$ 50
AFS securities, Number of securities in continuous unrealized loss position | security	8	8