Loans and Allowance for Credit Losses for Loans - Recorded Investment Based on Payment Activity - PCI Loans (Details) - PCI Loans $ in Thousands	Dec. 31, 2019 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 6,629,599
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	580,169
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	122,267
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	682,014
Commercial real estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	5,093,848
Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	151,301
Performing Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	6,559,439
Performing Loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	571,006
Performing Loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	120,356
Performing Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	653,997
Performing Loans | Commercial real estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	5,065,388
Performing Loans | Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	148,692
Non-Performing Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	70,160
Non-Performing Loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	9,163
Non-Performing Loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	1,911
Non-Performing Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	28,017
Non-Performing Loans | Commercial real estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	28,460
Non-Performing Loans | Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 2,609