Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 268,599	$ 327,440
Overnight investments	1,386,525	797,406
Investment in marketable equity securities	109,884	92,599
Investment securities available for sale	4,589,800	4,557,110
Investment securities held to maturity	2,214,829	2,184,653
Loans held for sale	53,232	45,505
Loans and leases	25,463,785	25,523,276
Allowance for loan and lease losses	(228,775)	(223,712)
Net loans and leases	25,235,010	25,299,564
Premises and equipment	1,203,674	1,204,179
Other real estate owned	43,306	48,030
Income earned not collected	113,812	109,903
Goodwill	236,347	236,347
Other intangible assets	67,053	72,298
Other assets	439,599	433,595
Total assets	35,961,670	35,408,629
Deposits [Abstract]
Noninterest-bearing deposits	12,376,913	11,882,670
Interest-bearing deposits	18,821,180	18,789,790
Total deposits	31,198,093	30,672,460
Securities sold under customer repurchase agreements	508,508	543,936
Debt, Long-term and Short-term, Combined Amount	189,594	193,556
Subordinated Debt	136,544	140,741
Long-term obligations	14,970	13,921
FDIC shared-loss payable	107,256	105,618
Other liabilities	283,396	249,443
Total liabilities	32,438,361	31,919,675
Shareholders' Equity
Preferred stock	0	0
Surplus	393,449	493,962
Retained earnings	3,325,335	3,218,551
Accumulated other comprehensive loss	(206,860)	(235,187)
Total shareholders' equity	3,523,309	3,488,954
Total liabilities and shareholders' equity	35,961,670	35,408,629
Class A Common Stock
Shareholders' Equity
Common stock	10,380	10,623
Class B Common Stock
Shareholders' Equity
Common stock	$ 1,005	$ 1,005