Accumulated Other Comprehensive Income (Loss) - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on sales of available for sale securities	$ 393	$ 1,285	$ 3,376	$ 4,016
Interest expense - subordinated debentures and term loans	2,076	2,089	6,315	6,136
Income tax expense	(6,337)	(8,478)	(21,027)	(23,050)
Total reclassifications for the period, net of tax	228	942	2,472	2,882
Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	310	1,015	2,667	3,173
Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	(82)	(73)	(195)	(291)
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	393	1,285	3,376	4,016
Income tax expense	(83)	(270)	(709)	(843)
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	22	20	52	77
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	$ (104)	$ (93)	$ (247)	$ (368)