Accumulated Other Comprehensive Income (Loss) - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on sales of available for sale securities	$ 1,817	$ 393	$ 9,497	$ 3,376
Interest expense - subordinated debentures and term loans	1,691	2,076	5,275	6,315
Income tax expense	(5,621)	(6,337)	(13,734)	(21,027)
Total reclassifications for the period, net of tax	36,210	36,757	103,465	116,630
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	1,203	228	6,989	2,472
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on sales of available for sale securities	1,817	393	9,497	3,376
Income tax expense	(382)	(83)	(1,994)	(709)
Total reclassifications for the period, net of tax	1,435	310	7,503	2,667
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	62	22	137	52
Total reclassifications for the period, net of tax	(232)	(82)	(514)	(195)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on cash flow hedges | Interest rate contracts
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - subordinated debentures and term loans	$ (294)	$ (104)	$ (651)	$ (247)