Commitments and Contingencies (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)
Other Commitments [Line Items]
VISA Class B Conversion Ratio	1.6298
Commitments to extend credit: | Home equity
Other Commitments [Line Items]
Contractual obligations	$ 209,455	$ 207,509
Commitments to extend credit: | Commercial real estate
Other Commitments [Line Items]
Contractual obligations	76,922	68,649
Commitments to extend credit: | Other commitments
Other Commitments [Line Items]
Contractual obligations	201,625	201,687
Standby letters of credit
Other Commitments [Line Items]
Contractual obligations	7,245	7,183
Commercial letters of credit
Other Commitments [Line Items]
Contractual obligations	$ 811	$ 811
Common Class B | VISA, Inc. (VISA)
Other Commitments [Line Items]
Investment Owned, Balance, Shares | shares	86,605
Common Class A | VISA, Inc. (VISA)
Other Commitments [Line Items]
Share Price | $ / shares	$ 156.19
Investment Owned, at Fair Value	$ 22,000