Goodwill and Other Intangible Assets - Finite-Lived Intangible Assets Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Gross Balance of CDI:
Balance, beginning of year	$ 145,212	$ 125,945	$ 125,945	$ 125,945	$ 125,945
Additions due to acquisitions	0	19,267	0	19,267	0
Balance, end of year	145,212	145,212	125,945	145,212	125,945
Accumulated amortization:
Balance, beginning of year	(50,662)	(46,596)	(34,104)	(42,633)	(25,387)
Amortization	(4,538)	(4,066)	(4,281)	(12,567)	(12,998)
Balance, end of year	(55,200)	(50,662)	(38,385)	(55,200)	(38,385)
Net intangible assets	$ 90,012	$ 94,550	$ 87,560	$ 90,012	$ 87,560