Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 168,146	$ 102,957	$ 116,172
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,431	21,082	19,465
Stock-based compensation	10,032	7,575	7,489
Provision for credit losses	11,869	8,101	1,884
Net amortization of premiums and accretion of discounts on securities and borrowings	24,310	22,080	26,949
Amortization of other intangible assets	11,327	9,169	9,919
Gains on securities transactions, net	(777)	(2,487)	(745)
Proceeds from sales of loans held for sale	572,439	144,790	85,452
Gains on sales of loans, net	(22,030)	(4,245)	(1,731)
Originations of loans held for sale	(425,713)	(134,328)	(91,463)
Gains on sales of assets, net	(1,358)	(2,776)	(18,087)
Net deferred income tax expense	27,154	16,453	11,455
FDIC loss-share receivable (excluding reimbursements)	1,291	3,326	20,792
Net change in:
Trading securities	0	14,233	31
Fair value of borrowings hedged by derivative transactions	6,158	1,473	1,364
Cash surrender value of bank owned life insurance	(6,694)	(6,815)	(6,392)
Accrued interest receivable	(3,262)	(2,480)	423
Other assets	46,167	(74,589)	15,867
Accrued expenses and other liabilities	(24,313)	31,410	(14,868)
Net cash provided by operating activities	419,177	154,929	183,976
Cash flows from investing activities:
Net loan originations and purchases	(1,379,218)	(1,756,578)	(778,300)
Investment securities held to maturity:
Purchases	(669,157)	(239,608)	(397,186)
Sales	0	11,666	0
Maturities, calls and principal repayments	325,766	402,485	347,531
Investment securities available for sale:
Purchases	(679,530)	(594,327)	(28,415)
Sales	4,782	140,640	62,025
Maturities, calls and principal repayments	867,998	142,588	153,673
Death benefit proceeds from bank owned life insurance	2,406	0	0
Proceeds from sales of real estate property and equipment	20,560	23,861	43,360
Purchases of real estate property and equipment	(20,707)	(34,040)	(21,862)
(Payments to) reimbursements from the FDIC	(213)	1,889	5,582
Cash and cash equivalents acquired in acquisitions	0	201,025	102,025
Net cash used in investing activities	(1,527,313)	(1,700,399)	(511,567)
Cash flows from financing activities:
Net change in deposits	1,477,157	1,051,660	1,300,011
Net change in short-term borrowings	3,969	873,123	(151,470)
Proceeds from issuance of long-term borrowings, net	385,000	162,792	0
Repayments of long-term borrowings	(769,182)	(970,000)	(275,000)
Proceeds from issuance of preferred stock, net	0	111,590	0
Dividends paid to preferred shareholders	(7,188)	(3,813)	0
Cash dividends paid to common shareholders	(111,813)	(102,279)	(88,119)
Purchase of common shares to treasury	(3,191)	(2,108)	(1,688)
Common stock issued, net	112,085	7,898	5,096
Net cash provided by financing activities	1,086,837	1,128,863	788,830
Net change in cash and cash equivalents	(21,299)	(416,607)	461,239
Cash and cash equivalents at beginning of year	413,800	830,407	369,168
Cash and cash equivalents at end of year	392,501	413,800	830,407
Supplemental disclosures of cash flow information:
Interest on deposits and borrowings	151,209	159,170	162,762
Federal and state income taxes	26,564	50,027	34,236
Supplemental schedule of non-cash investing activities:
Transfer of loans to other real estate owned	8,089	8,828	11,012
Loans transferred to loans held for sale	174,501	0	27,329
Non-cash assets acquired:
Loans	0	822,716	1,160,269
Premises and equipment	0	8,550	11,234
Bank owned life insurance	0	5,090	25,224
Accrued interest receivable	0	3,741	3,792
Goodwill	0	113,587	148,115
Other intangible assets	0	18,616	9,750
Other assets	0	49,831	52,349
Total non-cash assets acquired	0	1,349,283	1,634,737
Liabilities assumed:
Deposits	0	1,167,725	1,414,843
Short-term borrowings	0	57,087	16,796
Long-term borrowings	0	90,738	0
Accrued expenses and other liabilities	0	5,156	13,900
Total liabilities assumed	0	1,320,706	1,445,539
Net non-cash assets acquired	0	28,577	189,198
Net cash and cash equivalents acquired in acquisition	0	201,025	102,025
Common stock issued in acquisition	0	229,602	291,223
Held-to-maturity securities
Non-cash assets acquired:
Investments acquired	0	0	7,930
Available for sale securities
Non-cash assets acquired:
Investments acquired	$ 0	$ 327,152	$ 216,074