Loans and Allowance for Loan Losses Loans and Allowance for Loan Losses, Purchased Credit Impaired Loans (Details) - Receivables Acquired with Deteriorated Credit Quality [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Allowance for Loan Losses - Purchase Credit Impaired [Line Items]
Purchased Loans Contractually Required Principal And Interest	$ 94,312,000	$ 1,359,000	$ 19,960,000
Purchased Loans Cash Flows Expected To Be Collected	48,498,000	547,000	14,257,000
Purchased Credit Impaired Loans Acquisition Date Fair Value	$ 48,302,000	$ 547,000	$ 14,257,000