Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 102,957	$ 116,172	$ 131,961
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21,082	19,465	19,712
Stock-based compensation	7,575	7,489	6,055
Provision for credit losses	8,101	1,884	16,095
Net amortization of premiums and accretion of discounts on securities and borrowings	22,080	26,949	16,229
Amortization of other intangible assets	9,169	9,919	8,258
Gains on securities transactions, net	(2,487)	(745)	(14,678)
Proceeds from sales of loans held for sale	144,790	85,452	1,083,297
Gains on sales of loans, net	(4,245)	(1,731)	(33,695)
Originations of loans held for sale	(134,328)	(91,463)	(953,125)
Gains on sales of assets, net	(2,776)	(18,087)	(10,947)
Net deferred income tax expense	16,453	11,455	30,329
FDIC loss-share receivable (excluding reimbursements)	3,326	20,792	8,427
Net change in:
Trading securities	14,233	31	7,893
Fair value of borrowings hedged by derivative transactions or carried at fair value	1,473	1,364	731
Cash surrender value of bank owned life insurance	(6,815)	(6,392)	(5,962)
Accrued interest receivable	(2,480)	423	(1,589)
Other assets	(74,589)	15,867	(19,199)
Accrued expenses and other liabilities	31,410	(14,868)	(4,428)
Net cash provided by operating activities	154,929	183,976	285,364
Cash flows from investing activities:
Net loan originations	(570,513)	(649,616)	(368,724)
Loans purchased	(1,186,065)	(128,684)	(231,008)
Investment securities held to maturity:
Purchases	(239,608)	(397,186)	(619,299)
Sales	11,666	0	0
Maturities, calls and principal repayments	402,485	347,531	473,362
Investment securities available for sale:
Purchases	(594,327)	(28,415)	(289,181)
Sales	140,640	62,025	57,003
Maturities, calls and principal repayments	142,588	153,673	183,006
Death benefit proceeds from bank owned life insurance	0	0	1,821
Proceeds from sales of real estate property and equipment	23,861	43,360	18,034
Purchases of real estate property and equipment	(34,040)	(21,862)	(14,852)
Reimbursements from the FDIC	1,889	5,582	3,812
Cash and cash equivalents acquired in acquisitions	201,025	102,025	0
Net cash used in investing activities	(1,700,399)	(511,567)	(786,026)
Cash flows from financing activities:
Net change in deposits	1,051,660	1,300,011	55,244
Net change in short-term borrowings	873,123	(151,470)	127,132
Proceeds from issuance of long-term borrowings, net	162,792	0	125,000
Repayments of long-term borrowings	(970,000)	(275,000)	(26,133)
Proceeds from issuance of preferred stock, net	111,590	0	0
Redemption of junior subordinated debentures	0	0	(142,313)
Dividends paid to preferred shareholders	(3,813)	0	0
Cash dividends paid to common shareholders	(102,279)	(88,119)	(129,271)
Purchase of common shares to treasury	(2,108)	(1,688)	(768)
Common stock issued, net	7,898	5,096	7,839
Net cash provided by financing activities	1,128,863	788,830	16,730
Net change in cash and cash equivalents	(416,607)	461,239	(483,932)
Cash and cash equivalents at beginning of year	830,407	369,168	853,100
Cash and cash equivalents at end of year	413,800	830,407	369,168
Supplemental disclosures of cash flow information:
Interest on deposits and borrowings	159,170	162,762	167,860
Federal and state income taxes	50,027	34,236	15,317
Supplemental schedule of non-cash investing activities:
Transfer of loans to other real estate owned	8,828	11,012	19,679
Loans transferred to loans held for sale	0	27,329	0
Non-cash assets acquired:
Loans	825,465	1,160,269	0
Premises and equipment	8,550	11,234	0
Bank owned life insurance	5,090	25,224	0
Accrued interest receivable	3,741	3,792	0
Goodwill	109,991	149,300	0
Other intangible assets	19,330	9,750	0
Other assets	49,894	51,164	0
Total non-cash assets acquired	1,349,325	1,634,737	0
Liabilities assumed:
Deposits	1,167,775	1,414,843	0
Short-term borrowings	57,087	16,796	0
Long-term borrowings	90,738	0	0
Accrued expenses and other liabilities	5,148	13,900	0
Total liabilities assumed	1,320,748	1,445,539	0
Net non-cash assets acquired	28,577	189,198	0
Net cash and cash equivalents acquired in acquisition	201,025	102,025	0
Common stock issued in acquisition	229,602	291,223	0
Held-to-maturity Securities [Member]
Non-cash assets acquired:
Investments acquired	0	7,930	0
Available for sale securities [Member]
Non-cash assets acquired:
Investments acquired	$ 327,264	$ 216,074	$ 0