Loans Loans (Analysis of Purchased Credit Impaired - Accretable Yield Rollforward) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans, Analysis of Purchased Credit Impaired Loans, Accretable Yield Rollforward [Abstract]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield	$ 31,176	$ 45,191	$ 58,981	$ 73,849
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(12,357)	(16,266)	(21,919)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans	158	148	1,681
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	$ (1,500)	$ 2,624	$ 8,732