Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income
Interest and fees on loans	$ 156,818	$ 132,485
Interest on investment securities:
Taxable	12,419	4,756
Tax-exempt	5,556	4,235
Dividends on nonmarketable equity securities	1,901	621
Interest on deposits with the Federal Reserve Bank, other banks and Federal funds sold	1,240	799
Total interest income	177,934	142,896
Interest expense
Interest on deposits	15,917	8,916
Interest on collateralized customer deposits	524	150
Interest on short-term borrowings	8,166	1,508
Interest on long-term borrowings	1,464	2,225
Total interest expense	26,071	12,799
Net interest income	151,863	130,097
Provision for loan losses	6,256	4,050
Net interest income after provision for loan losses	145,607	126,047
Noninterest income
Service charges and fees on deposit accounts	8,463	8,004
Wealth management revenue	6,311	5,827
Other charges and fees for customer services	5,754	8,891
Net gain on sale of loans and other mortgage banking revenue	12,535	9,160
Net gain on sale of investment securities	0	90
Other	7,491	6,038
Total noninterest income	40,554	38,010
Operating expenses
Salaries, wages and employee benefits	56,105	59,894
Occupancy	8,011	7,392
Equipment and software	7,659	8,517
Outside processing and service fees	11,332	7,511
Merger expenses	0	4,167
Other	20,251	16,715
Total operating expenses	103,358	104,196
Income before income taxes	82,803	59,861
Income tax expense	12,633	12,257
Net income	$ 70,170	$ 47,604
Earnings per common share:
Basic earnings per common share (dollars per share)	$ 0.99	$ 0.67
Diluted earnings per common share (dollars per share)	0.97	0.67
Cash dividends declared per common share (dollars per share)	$ 0.28	$ 0.27