Summary of Significant Accounting Policies (Other Intangible Assets) (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years
Core deposit intangible assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Core deposit intangible assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years