Goodwill and Other Intangible Assets (Changes in the Carrying amount of Goodwill by Reporting Unit) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Goodwill [Line Items]
Beginning Balance	$ 465,547
Ending Balance	465,697
Acquisition of East West Markets, LLC
Goodwill [Line Items]
Acquisition of East West Markets, LLC	150
Consumer and Business Banking
Goodwill [Line Items]
Beginning Balance	353,321
Ending Balance	353,321
Consumer and Business Banking | Acquisition of East West Markets, LLC
Goodwill [Line Items]
Acquisition of East West Markets, LLC	0
Commercial Banking
Goodwill [Line Items]
Beginning Balance	112,226
Ending Balance	112,376
Commercial Banking | Acquisition of East West Markets, LLC
Goodwill [Line Items]
Acquisition of East West Markets, LLC	$ 150