Goodwill and Other Intangible Assets (Amortization Expense of Core Deposit Intangibles) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of core deposit intangibles	$ 6,935	$ 8,086	$ 9,234
Core Deposit Intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of core deposit intangibles	6,900	8,100	$ 9,200
($ in thousands)
2018	5,883
2019	4,864
2020	3,846
2021	2,833
2022	1,865
Thereafter	1,763
Total	$ 21,054	$ 27,989