Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest and dividend income
Loans and leases, including fees	$ 1,160,919	$ 1,086,662	$ 802,947
Mortgage loans held for sale, including fees	6,710	3,748	4,679
Taxable securities	117,428	107,137	87,359
Tax-exempt securities	8,358	10,634	8,835
Other	16,593	13,448	9,963
Total interest and dividend income	1,310,008	1,221,629	913,783
Interest expense
Deposits	267,227	160,952	79,833
Short-term borrowings	15,739	14,682	7,557
Long-term debt	37,396	32,747	17,547
Total interest expense	320,362	208,381	104,937
Net interest income	989,646	1,013,248	808,846
Provision for credit losses	41,657	40,385	51,708
Net interest income after provision for credit losses	947,989	972,863	757,138
Non-interest income
Loss on sale of available-for-sale securities	(979)	(49,900)	(148)
Other non-interest income	19,945	15,896	18,004
Total non-interest income	234,360	152,562	202,147
Non-interest expense
Salaries and employee benefits	411,869	414,741	379,527
Net occupancy and equipment	79,773	77,246	70,663
Communication and delivery	14,578	15,951	14,252
Marketing and business development	14,161	18,371	13,999
Computer services expense	38,108	39,680	36,790
Professional services	33,284	28,698	48,545
Credit and other loan-related expense	14,448	19,088	18,411
Insurance	17,365	25,274	21,815
Travel and entertainment	10,432	10,035	11,287
Amortization of acquisition intangibles	18,464	21,678	12,590
Impairment of long-lived assets and other losses	925	27,780	12,246
Other non-interest expense	29,349	24,356	26,281
Total non-interest expense	682,756	722,898	666,406
Income before income tax expense	499,593	402,527	292,879
Income tax expense	115,438	32,278	150,466
Net income	384,155	370,249	142,413
Less: Preferred stock dividends	12,602	9,095	9,095
Net income available to common shareholders	371,553	361,154	133,318
Less: Earnings allocated to unvested restricted stock	3,559	3,583	1,210
Earnings allocated to common shareholders	$ 367,994	$ 357,571	$ 132,108
Earnings per common share - basic (in usd per share)	$ 6.97	$ 6.50	$ 2.61
Earnings per common share - diluted (in usd per share)	6.92	6.46	2.59
Cash dividends declared per common share (in usd per share)	$ 1.76	$ 1.56	$ 1.46
Comprehensive income
Net income	$ 384,155	$ 370,249	$ 142,413
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period (net of tax effects of $24,266, $10,870, and $6,244, respectively)	85,308	(40,895)	(11,596)
Less: Reclassification adjustment for gains (losses) included in net income (net of tax effects of $242, $10,479, and $52, respectively)	(737)	(39,421)	(96)
Unrealized gains (losses) on securities, net of tax	86,045	(1,474)	(11,500)
Fair value of derivative instruments designated as cash flow hedges:
Change in fair value of derivative instruments designated as cash flow hedges during the period (net of tax effects of $495, $1,174, and $329, respectively)	1,078	4,416	(611)
Less: Reclassification adjustment for gains (losses) included in net income (net of tax effects of $120, $52, and $210, respectively)	(388)	(196)	(390)
Fair value of derivative instruments designated as cash flow hedges, net of tax	1,466	4,612	(221)
Other comprehensive income (loss), net of tax	87,511	3,138	(11,721)
Comprehensive income	471,666	373,387	130,692
Mortgage income
Non-interest income
Non-interest income	63,030	46,424	63,570
Service charges on deposit accounts
Non-interest income
Non-interest income	51,836	52,803	47,678
Title revenue
Non-interest income
Non-interest income	25,928	24,149	21,972
Commission income
Non-interest income
Non-interest income	16,937	8,869	6,020
Broker commissions
Non-interest income
Non-interest income	8,280	9,195	9,161
ATM and debit card fee income
Non-interest income
Non-interest income	11,871	10,295	10,199
Credit card and merchant-related income
Non-interest income
Non-interest income	13,260	12,540	10,904
Trust department income
Non-interest income
Non-interest income	17,058	15,981	9,705
Income from bank owned life insurance
Non-interest income
Non-interest income	$ 7,194	$ 6,310	$ 5,082