Goodwill and Other Intangible Assets (Goodwill Reporting Unit) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning	$ 465,547
Goodwill, end	465,697
East West Markets, LLC
Goodwill [Roll Forward]
Acquisition of East West Markets, LLC	150
Consumer and Business Banking
Goodwill [Roll Forward]
Goodwill, beginning	353,321
Goodwill, end	353,321
Consumer and Business Banking | East West Markets, LLC
Goodwill [Roll Forward]
Acquisition of East West Markets, LLC	0
Commercial Banking
Goodwill [Roll Forward]
Goodwill, beginning	112,226
Goodwill, end	112,376
Commercial Banking | East West Markets, LLC
Goodwill [Roll Forward]
Acquisition of East West Markets, LLC	$ 150