Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Beginning balance of allowance for off-balance sheet credit losses	$ 10,174	$ 9,795	$ 8,640	$ 11,434
Provision for off-balance sheet credit losses	2,094	995	3,065	(644)
Ending balance of allowance for off-balance sheet credit losses	12,268	$ 10,790	12,268	$ 10,790
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet liability	8,074,723		8,074,723		$ 8,066,655
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet liability	$ 252,246		$ 252,246		$ 261,405