Other Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Net carrying amount	$ 28,556	$ 34,271
Core deposit intangible assets
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	56,456	59,143
Accumulated amortization	27,900	24,884
Net carrying amount	$ 28,556	$ 34,259