Goodwill and Other Intangible Assets (Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Goodwill [Roll Forward]
Balance as of December 31, 2019		$ 497,267
Goodwill impairment		(44,877)	$ 0
Balance as of September 30, 2020	$ 452,390	452,390
Community Banking Reporting Unit
Goodwill [Roll Forward]
Balance as of December 31, 2019		256,323
Goodwill impairment		0
Balance as of September 30, 2020	256,323	256,323
Wholesale Banking Reporting Unit
Goodwill [Roll Forward]
Balance as of December 31, 2019		171,636
Goodwill impairment		0
Balance as of September 30, 2020	171,636	171,636
Consumer Mortgage Reporting Unit
Goodwill [Roll Forward]
Balance as of December 31, 2019		44,877
Goodwill impairment	(44,900)	(44,877)
Balance as of September 30, 2020	0	0
Wealth Management Reporting Unit
Goodwill [Roll Forward]
Balance as of December 31, 2019		24,431
Goodwill impairment		0
Balance as of September 30, 2020	$ 24,431	$ 24,431