Goodwill, Core Deposit Intangibles and Other Intangible Assets (Changes in Capitalized Mortgage and Commercial Servicing Rights) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Servicing Asset at Fair Value, Amount [Roll Forward]
Sale of mortgage servicing rights	$ (6,900)
Mortgage Servicing Rights
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of period	32,088	$ 30,314
Originations	7,149	12,266
Amortization	(9,049)	(10,492)
Sale of mortgage servicing rights	(6,940)	0
Balance at end of period	23,248	32,088
Fair value of mortgage servicing rights	$ 37,081	$ 45,210
Servicing rights, net to servicing portfolio (as a percent)	0.65%	0.74%
Commercial Servicing Rights
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of period	$ 3,690	$ 4,611
Originations	209	628
Amortization	(1,311)	(1,706)
Purchased commercial servicing rights	0	190
Valuation allowance on commercial servicing rights	21	(33)
Balance at end of period	2,609	3,690
Fair value of mortgage servicing rights	$ 3,221	$ 4,127
Servicing rights, net to servicing portfolio (as a percent)	1.87%	2.24%