Revenue from Contracts with Customers Revenue from Contracts with Customers (Schedule of Trust Fees) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Trust Fees [Line Items]
Fees and Commissions, Fiduciary and Trust Activities (Deprecated 2018-01-31)	$ 147,964	$ 135,159	$ 121,795
Private Client [Member]
Trust Fees [Line Items]
Fees and Commissions, Fiduciary and Trust Activities (Deprecated 2018-01-31)	111,533	100,358	90,992
Institutional [Member]
Trust Fees [Line Items]
Fees and Commissions, Fiduciary and Trust Activities (Deprecated 2018-01-31)	29,241	27,477	24,565
Other Trust Fees [Member]
Trust Fees [Line Items]
Fees and Commissions, Fiduciary and Trust Activities (Deprecated 2018-01-31)	$ 7,190	$ 7,324	$ 6,238