Non-performing Loans - Collateral Pledged Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	$ 4,030,365	$ 3,634,596
Real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	1,049,873	920,998
Real estate | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	651,680	751,019
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	2,321,608	2,047,646
Commercial | Owner occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	503,127	519,577
Commercial | Non–owner occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	1,019,171	973,331
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	761,735	$ 505,859
Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	4,260
Collateral Pledged | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	4,260
Collateral Pledged | Commercial | Owner occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	3,018
Collateral Pledged | Commercial | Non–owner occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	488
Collateral Pledged | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total collateral dependent loans	$ 754