Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Assets
Cash and due from banks		$ 229,631	$ 234,766
Money market and other interest-earning investments		101,119	41,571
Total cash and cash equivalents		330,750	276,337
Equity securities, at fair value		2,518	6,842
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		5,601,534	5,385,091
Federal Home Loan Bank/Federal Reserve Bank stock, at cost		169,452	164,099
Loans held for sale, at fair value		85,091	46,898
Loans:
Total loans		13,892,509	12,117,524
Allowance for loan losses	[1]	(131,388)	(54,619)
Net loans		13,761,121	12,062,905
Premises and equipment, net		463,253	490,925
Operating lease right-of-use assets		77,482	95,477
Accrued interest receivable		83,052	85,123
Goodwill		1,036,994	1,036,994
Other intangible assets		49,258	60,105
Company-owned life insurance		455,975	448,967
Other assets		343,996	251,904
Total assets		22,460,476	20,411,667
Deposits:
Noninterest-bearing demand		5,463,007	4,042,286
Interest-bearing:
Checking and NOW		4,588,432	4,149,639
Savings		3,287,302	2,845,423
Money market		1,904,404	1,833,819
Other time deposits		1,206,658	1,589,988
Brokered certificates of deposit		56,691	92,242
Total deposits		16,506,494	14,553,397
Federal funds purchased and interbank borrowings		1,259	350,414
Securities sold under agreements to repurchase		399,141	327,782
Federal Home Loan Bank advances		2,087,648	1,822,847
Other borrowings		237,683	243,685
Operating lease liabilities		88,552	99,500
Accrued expenses and other liabilities		218,550	161,589
Total liabilities		19,539,327	17,559,214
Shareholders' Equity
Preferred stock, 2,000 shares authorized, no shares issued or outstanding		0	0
Common stock, $1.00 per share stated value, 300,000 shares authorized,    165,333 and 169,616 shares issued and outstanding, respectively		165,333	169,616
Capital surplus		1,873,483	1,944,445
Retained earnings		733,049	682,185
Accumulated other comprehensive income (loss), net of tax		149,284	56,207
Total shareholders' equity		2,921,149	2,852,453
Total liabilities and shareholders' equity		22,460,476	20,411,667
Commercial
Loans:
Total loans		4,264,568	2,890,296
Allowance for loan losses		(28,393)	(22,585)
Commercial real estate
Loans:
Total loans		5,701,493	5,166,792
Allowance for loan losses		(75,912)	(21,588)
Residential real estate
Loans:
Total loans		2,265,299	2,334,289
Allowance for loan losses		(13,924)	(2,299)
Consumer
Loans:
Total loans		1,661,149	1,726,147
Allowance for loan losses			(8,147)
U.S. Treasury
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		10,230	17,682
U.S. government-sponsored entities and agencies
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		491,541	592,984
Mortgage-backed securities
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		3,382,280	3,183,861
States and political subdivisions
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		1,426,495	1,275,643
Other securities
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale		$ 290,988	$ 314,921

[1] Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.