Loans and Allowance for Credit Losses - Amortized cost basis of collateral-dependent loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans and leases receivable, net of deferred income	$ 7,880,255	$ 7,545,748
Commercial
Loans and leases receivable, net of deferred income	1,524,613	1,545,906
Income producing - commercial real estate
Loans and leases receivable, net of deferred income	3,724,839	3,702,747
Owner occupied - Commercial real estate
Loans and leases receivable, net of deferred income	997,645	985,409
Real estate mortgage residential
Loans and leases receivable, net of deferred income	82,385	104,221
Construction - commercial and residential
Loans and leases receivable, net of deferred income	879,144	1,125,244
Home equity
Loans and leases receivable, net of deferred income	72,648	80,061
Other consumer
Loans and leases receivable, net of deferred income	2,509	$ 2,160
Business or Other Assets
Loans and leases receivable, net of deferred income	17,276
Business or Other Assets | Commercial
Loans and leases receivable, net of deferred income	14,075
Business or Other Assets | Income producing - commercial real estate
Loans and leases receivable, net of deferred income	3,193
Business or Other Assets | Other consumer
Loans and leases receivable, net of deferred income	8
Real Estate
Loans and leases receivable, net of deferred income	50,944
Real Estate | Commercial
Loans and leases receivable, net of deferred income	2,948
Real Estate | Income producing - commercial real estate
Loans and leases receivable, net of deferred income	26,063
Real Estate | Owner occupied - Commercial real estate
Loans and leases receivable, net of deferred income	14,215
Real Estate | Real estate mortgage residential
Loans and leases receivable, net of deferred income	5,335
Real Estate | Construction - commercial and residential
Loans and leases receivable, net of deferred income	2,274
Real Estate | Home equity
Loans and leases receivable, net of deferred income	$ 109