Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Loans and lease financing	$ 462,675	$ 428,419	$ 405,702
Available-for-sale securities	102,272	83,019	73,615
Other	5,821	7,082	4,529
Total interest income	570,768	518,520	483,846
Interest expense
Deposits	41,944	26,650	22,314
Short-term borrowings and long-term debt	20	198	207
Total interest expense	41,964	26,848	22,521
Net interest income	528,804	491,672	461,325
Provision for loan and lease losses	18,500	8,600	9,900
Net interest income after provision for loan and lease losses	510,304	483,072	451,425
Noninterest income
Service charges on deposit accounts	35,807	37,392	40,058
Credit and debit card fees	64,049	65,262	64,916
Other service charges and fees	34,063	35,355	38,641
Trust and investment services income	30,485	29,440	29,671
Bank-owned life insurance	13,283	15,021	9,976
Investment securities gains, net		27,277	12,321
Other	27,918	16,290	23,528
Total noninterest income	205,605	226,037	219,111
Noninterest expense
Salaries and employee benefits	175,351	169,233	170,233
Contracted services and professional fees	45,011	45,345	42,663
Occupancy	23,485	21,606	18,401
Equipment	17,247	16,912	15,836
Regulatory assessment and fees	14,907	12,972	9,490
Advertising and marketing	6,191	6,127	5,472
Card rewards program	23,363	22,459	23,969
Other	41,999	42,626	41,245
Total noninterest expense	347,554	337,280	327,309
Income before provision for income taxes	368,355	371,829	343,227
Provision for income taxes	184,673	141,651	129,447
Net income	$ 183,682	$ 230,178	$ 213,780
Basic earnings per share (in dollars per share)	$ 1.32	$ 1.65	$ 1.53
Diluted earnings per share (in dollars per share)	1.32	1.65	$ 1.53
Dividends declared per share (in dollars per share)	$ 0.88	$ 0.62
Basic weighted-average outstanding shares (in shares)	139,560,305	139,487,762	139,459,620
Diluted weighted-average outstanding shares (in shares)	139,656,993	139,492,608	139,459,620