Revenue from Contracts with Customers - Disaggregation of Revenue by Source (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Wealth management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 90,963	$ 81,766	$ 76,018
Brokerage and insurance product commissions
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22,391	22,863	25,519
Trust
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13,263	12,547	11,993
Asset management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	55,309	46,356	38,506
Mortgage broker fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,188	1,565	2,834
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	36,404	34,513	31,210
Administrative services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,625	4,165	4,409
Card related fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,441	5,858	5,495
Other deposit related fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 11,892	$ 11,127	$ 9,555