Goodwill and Other Intangible Assets - Rollforward of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Finite-lived Intangible Assets [Roll Forward]
CDI and CRI Balance, beginning of period	$ 100,550	$ 109,646	$ 117,573	$ 109,646	$ 117,573
CDI and CRI Balance, end of period	100,550	100,550	109,646	100,550	109,646
Finite-lived Intangible Assets Acquired	0		0	750	0
Accumulated Amortization, beginning of period	(79,238)	(86,005)	(83,127)	(86,005)	(79,179)
Amortization expense	(2,889)	(3,079)	(3,882)	(5,968)	(7,830)
Accumulated Amortization, end of period	(82,127)	$ (79,238)	(79,082)	(82,127)	(79,082)
Net CDI and CRI, end of period	18,423		30,564	18,423	30,564
Finite Lived Intangible Assets Fully Amortized Portion	$ 0		$ 7,927	$ 9,846	$ 7,927