Fair Value Fair Value (Impaired Financing Receivables Additional Information) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Impaired Financing Receivables Additional Information [Line Items]
Book Value Of Impaired Loans Carried At Fair Value	$ 7,470	$ 6,379
Partial Charge-Offs On Impaired Loans carried at Fair Value	2,822	3,681
Impaired Financing Receivable, Related Allowance	5,102	548
impaired Financing Receivable, loans not held at Fair Value, Carrying Amount	61,370	63,895
Impaired Financing Receivable, Recorded Investment	73,609	70,426	$ 77,998
Impaired Loan Fair Value	7,137	5,983
Impaired Financing Receivable, loans not held at Fair Value, Recorded Investment	66,139	64,047
Partial Charge-offs on Impaired Loans carried at Cost	7,124	21,262
Impaired Financing Receivable, Carrying Value	68,507	69,878
Partial Charge-Offs On Impaired Loans	9,946	24,943
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	5,102	548
Financing Receivable, not collateral dependent [Domain]
Schedule of Impaired Financing Receivables Additional Information [Line Items]
Impaired Financing Receivable, Related Allowance	4,769	152
Commercial Receivables, excluding Commercial, Financial, and Agricultural [Domain]
Schedule of Impaired Financing Receivables Additional Information [Line Items]
Impaired Financing Receivable, Related Allowance	$ 333	$ 396