Goodwill and Other Intangible Assets - Changes in Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period			$ 111,110
Amortization of intangibles	$ (3,332)	$ (3,369)	(6,676)	$ (6,782)
Total	103,759		103,759		$ 111,110
Core deposit premiums, end of period	103,759		103,759		111,110
Core Deposit Premium
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period			97,363	111,808	111,808
Disposition of intangible asset			(674)		(2,324)
Amortization of intangibles			(5,990)		(12,121)
Total	90,699		90,699		97,363
Core deposit premiums, end of period	90,699		90,699		97,363
Books of Business Intangible
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period			13,747	$ 15,532	15,532
Disposition of intangible asset			0		(413)
Amortization of intangibles			(687)		(1,372)
Total	13,060		13,060		13,747
Core deposit premiums, end of period	$ 13,060		$ 13,060		$ 13,747