Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income:
Loans and loans held for sale	$ 682,328	$ 635,872	$ 410,299
Investment securities:
Taxable	128,363	108,824	85,030
Tax-exempt	21,807	21,107	15,354
Total investment securities interest	150,170	129,931	100,384
Total interest income	832,498	765,803	510,683
Interest expense:
Interest bearing	2,963	2,543	987
Savings and money market accounts	22,101	24,406	20,563
Certificates and other time deposits	10,844	9,649	11,723
Securities sold under agreements to repurchase	991	1,240	1,157
Wholesale borrowings	6,277	3,893	4,423
Long-term debt	13,754	13,287	0
Total interest expense	56,930	55,018	38,853
Net interest income	775,568	710,785	471,830
Provision for loan losses	52,279	33,684	54,698
Net interest income after provision for loan losses	723,289	677,101	417,132
Noninterest income:
Trust department income	39,949	34,770	23,143
Service charges on deposits	71,457	74,399	57,737
Credit card fees	52,666	50,542	43,569
ATM and other service fees	24,179	19,155	14,792
Bank owned life insurance income	19,177	16,926	12,140
Investment services and insurance	15,145	12,777	8,990
Investment securities gains/(losses), net	166	(2,803)	3,786
Loan sales and servicing income	16,044	23,069	27,031
Other operating income	42,741	41,508	32,416
Total noninterest income	281,524	270,343	223,604
Noninterest expense:
Salaries, wages, pension and employee benefits	358,970	354,016	245,192
Net occupancy expense	59,436	49,510	31,754
Equipment expense	48,499	41,875	29,243
Stationery, supplies and postage	15,587	14,199	8,800
Bankcard, loan processing and other costs	45,625	71,929	34,195
Professional services	21,813	40,680	23,480
Amortization of intangibles	11,735	8,392	1,866
FDIC insurance expense	20,481	17,707	10,753
Other operating expense	82,773	85,945	65,654
Total noninterest expense	664,919	684,253	450,937
Income before income tax expense	339,894	263,191	189,799
Income tax expense	101,943	79,507	55,693
Net income	237,951	183,684	134,106
Less: Net income allocated to participating securities	1,930	1,545	0
Preferred Stock dividends	5,876	5,337	0
Net income attributable to common shareholders	$ 230,145	$ 176,802	$ 134,106
Basic earnings per common share	$ 1.39	$ 1.18	$ 1.22
Diluted earnings per common share	$ 1.39	$ 1.18	$ 1.22
Cash dividend per common share	$ 0.64	$ 0.64	$ 0.64
Weighted average number of common shares outstanding - basic	165,296	149,607	109,518
Weighted average number of common shares outstanding - diluted	166,054	150,421	109,518