Condensed Parent Company Information - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 232,345	$ 352,428	$ 473,532
Cash flows from investing activities
Proceeds from principal paydowns of securities available for sale	9,289	1,455	178
Other, net	7,645	(3,986)	10,911
Net cash provided by (used in) investing activities	(2,276,431)	(1,910,459)	(4,497)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long term debt	273,565	21,000	24,515
Repayment of long term debt	(157,933)	(35,360)	(35,278)
Dividends paid to stockholders	(77,013)	(80,392)	(81,212)
Net cash provided by (used in) financing activities	1,991,505	1,566,046	(569,086)
Net (decrease) increase in cash	(52,581)	8,015	(100,051)
CASH AND DUE FROM BANKS, BEGINNING	356,455	348,440	448,491
CASH AND DUE FROM BANKS, ENDING	303,874	356,455	348,440
Hancock [Member]
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities - principally dividends received from subsidiaries	30,527	126,491	257,251
Net cash provided by operating activities	30,527	126,491	257,251
Cash flows from investing activities
Contribution of capital to subsidiary	(90)		(870)
Proceeds from principal paydowns of securities available for sale	12,863	12,664	18,685
Other, net	1,629		(5,630)
Net cash provided by (used in) investing activities	14,402	12,664	12,185
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long term debt	269,004
Repayment of long term debt	(149,600)	(35,200)	(35,200)
Dividends paid to stockholders	(77,474)	(80,392)	(81,673)
Stock transactions, net	(95,266)	(45,130)	(112,266)
Net cash provided by (used in) financing activities	(53,336)	(160,722)	(229,139)
Net (decrease) increase in cash	(8,407)	(21,567)	40,297
CASH AND DUE FROM BANKS, BEGINNING	44,771	66,338	26,041
CASH AND DUE FROM BANKS, ENDING	$ 36,364	$ 44,771	$ 66,338