Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 22,477,409	$ 19,787,876
Loan losses, allowance	288,645	94,777
Loans and Leases Receivable, Net Amount	22,188,764	19,693,099
Commercial real estate- owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,748,075	2,669,766
Commercial real estate- Non-owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,220,452	5,039,452
Consumer real estate – mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,041,019	3,068,625
Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,728,439	2,430,483
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	8,395,963	6,290,296
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 343,461	$ 289,254