Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 483,666	$ 446,558
Interest-bearing deposits in other financial institutions	199,702	149,175
Federal funds sold and securities purchased under agreements to resell	32,650	46,500
Investment securities held to maturity, at amortized cost	2,282,853	1,273,536
Investment securities available for sale, at fair value	4,043,446	4,680,226
Federal Home Loan Bank and Federal Reserve Bank stocks, at cost	165,331	140,001
Residential loans held for sale (a)	85,544	108,010
Commercial loans held for sale	0	12,474
Loans	20,784,991	20,054,716
Allowance for loan losses	(265,880)	(278,335)
Loans, net	20,519,111	19,776,381
Bank and corporate owned life insurance	591,057	585,290
Tax credit investments	147,099	67,860
Trading assets	69,675	52,398
Premises and equipment, net	330,963	330,315
Goodwill	976,239	971,951
Mortgage servicing rights, net	58,384	61,476
Other intangible assets, net	15,580	15,377
Other assets	482,294	421,787
Total assets	30,483,594	29,139,315
Liabilities and stockholders' equity
Noninterest-bearing demand deposits	5,478,416	5,392,208
Interest-bearing deposits	17,307,546	16,496,240
Total deposits	22,785,962	21,888,448
Federal funds purchased and securities sold under agreements to repurchase	324,815	508,347
Other short-term funding	351,467	583,688
Long-term funding	3,397,450	2,761,795
Trading liabilities	67,660	51,103
Accrued expenses and other liabilities	318,797	254,622
Total liabilities	27,246,151	26,048,003
Stockholders’ equity
Preferred equity	159,929	159,929
Common stock	1,618	1,630
Surplus	1,454,188	1,459,498
Retained earnings	1,819,230	1,695,764
Accumulated other comprehensive income (loss)	(62,758)	(54,679)
Treasury stock, at cost	(134,764)	(170,830)
Total common equity	3,077,514	2,931,383
Total stockholders’ equity	3,237,443	3,091,312
Total liabilities and stockholders’ equity	$ 30,483,594	$ 29,139,315
Preferred shares issued	165,000	165,000
Preferred shares authorized (par value $1.00 per share)	750,000	750,000
Common shares issued	161,751,975	163,030,209
Common shares authorized (par value $0.01 per share)	250,000,000	250,000,000
Treasury shares of common stock	8,908,448	10,909,362