Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
INTEREST INCOME
Loans	$ 308,325	$ 245,278	$ 229,665
Securities:
Taxable interest	75,327	76,204	75,202
Tax-exempt interest	43,598	39,209	40,399
Total securities income	118,925	115,413	115,601
Federal funds and resell agreements	697	259	193
Interest-bearing due from banks	2,356	2,525	1,918
Trading securities	378	396	964
Total interest income	430,681	363,871	348,341
INTEREST EXPENSE
Deposits	14,269	12,242	13,183
Federal funds and repurchase agreements	1,785	1,616	1,739
Other	2,560	(42)	150
Total interest expense	18,614	13,816	15,072
Net interest income	412,067	350,055	333,269
Provision for loan losses	15,500	17,000	17,500
Net interest income after provision for loan losses	396,567	333,055	315,769
NONINTEREST INCOME
Trust and securities processing	262,056	288,054	265,948
Trading and investment banking	20,218	19,398	20,641
Service charges on deposit accounts	86,460	85,299	84,133
Insurance fees and commissions	2,530	3,011	3,727
Brokerage fees	11,753	10,761	11,470
Bankcard fees	69,211	67,250	62,031
Gains on sales of securities available for sale, net	10,402	4,127	8,542
Equity (losses) earnings on alternative investments	(12,188)	3,975	19,048
Other	16,012	16,813	16,293
Total noninterest income	466,454	498,688	491,833
NONINTEREST EXPENSE
Salaries and employee benefits	406,472	358,569	339,691
Occupancy, net	43,861	40,197	39,291
Equipment	63,533	53,609	49,207
Supplies and services	18,579	20,411	20,387
Marketing and business development	23,730	24,148	22,703
Processing fees	51,328	56,049	57,791
Legal and consulting	26,390	20,407	18,703
Bankcard	20,288	19,594	18,381
Amortization of other intangible assets	12,090	12,193	13,218
Regulatory fees	12,125	10,445	9,129
Contingency reserve		20,272
Other	25,340	29,786	34,703
Total noninterest expense	703,736	665,680	623,204
Income before income taxes	159,285	166,063	184,398
Income tax expense	43,212	45,408	50,433
Net income	$ 116,073	$ 120,655	$ 133,965
PER SHARE DATA
Net income - basic	$ 2.46	$ 2.69	$ 3.25
Net income - diluted	$ 2.44	$ 2.65	$ 3.20
Weighted average shares outstanding - basic	47,126,252	44,844,578	41,275,839
Weighted average shares outstanding - diluted	47,579,334	45,445,283	41,838,580