CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Preferred Stock	Preferred Stock and Additional Paid-In Capital	Common Stock	Common Stock and Additional Paid-In Capital	Retained Earnings	Treasury Stock	AOCI, net of tax
BALANCE (in shares) at Dec. 31, 2012				85,710		140,294,092
BALANCE at Dec. 31, 2012	[1]	$ 2,385,991			$ 83,027		$ 1,464,896	$ 1,155,697	$ (322,298)	$ 4,669
Increase (Decrease) in Stockholders' Equity
Net income	[1]	293,324						293,324
Other comprehensive income (loss)		(35,128)								(35,128)
Stock compensation costs		13,548					13,548
Tax benefit from stock compensation plans, net		5,522					5,522
Net activity of common stock pursuant to various stock compensation plans and agreements (in shares)						(230,469)
Net activity of common stock pursuant to various stock compensation plans and agreements		(10,149)					4,840		(14,989)
Preferred stock dividends		(3,428)						(3,428)
Common stock dividends		(83,315)						(83,315)
Conversion of Series A preferred stock into common stock (in shares)				(85,710)		5,594,080
Conversion of Series A preferred stock into common stock		$ 0			(83,027)		83,027
Purchase of treasury stock pursuant to the Stock Repurchase Plan (in shares)		(8,026,807)				(8,026,807)
Purchase of treasury stock pursuant to the Stock Repurchase Plan		$ (199,992)							(199,992)
BALANCE (in shares) at Dec. 31, 2013				0		137,630,896
BALANCE at Dec. 31, 2013	[1]	2,366,373			0		1,571,833	1,362,278	(537,279)	(30,459)
Increase (Decrease) in Stockholders' Equity
Net income	[1]	345,878						345,878
Other comprehensive income (loss)		34,696								34,696
Stock compensation costs		13,883					13,883
Tax benefit from stock compensation plans, net		6,513					6,513
Net activity of common stock pursuant to various stock compensation plans and agreements (in shares)						368,240
Net activity of common stock pursuant to various stock compensation plans and agreements		(2,902)					7,803		(10,705)
Common stock dividends		(104,015)						(104,015)
Issuance of commons stock pursuant to MetroCorp Bancshares, Inc. (“MetroCorp”) acquisition (in shares)						5,583,093
Issuance of common stock pursuant to MetroCorp Bancshares, Inc. (“MetroCorp”) acquisition		190,830					73,044		117,786
Warrant acquired pursuant to MetroCorp acquisition		4,855					4,855
BALANCE (in shares) at Dec. 31, 2014				0		143,582,229
BALANCE at Dec. 31, 2014	[1]	2,856,111			0		1,677,931	1,604,141	(430,198)	4,237
Increase (Decrease) in Stockholders' Equity
Net income		384,677	[1]					384,677
Other comprehensive income (loss)		(19,178)								(19,178)
Stock compensation costs		16,502					16,502
Tax benefit from stock compensation plans, net		3,291					3,291
Net activity of common stock pursuant to various stock compensation plans and agreements (in shares)						327,004
Net activity of common stock pursuant to various stock compensation plans and agreements		(2,229)					3,735		(5,964)
Common stock dividends		(116,224)						(116,224)
BALANCE (in shares) at Dec. 31, 2015				0		143,909,233
BALANCE at Dec. 31, 2015		$ 3,122,950	[1]		$ 0		$ 1,701,459	$ 1,872,594	$ (436,162)	$ (14,941)

[1] Prior period was restated to reflect the retrospective application of adopting the new accounting guidance related to the Company’s investments in qualified affordable housing projects Accounting Standards Update (“ASU”) 2014-01. Please see Note 9 — Investments in Qualified Affordable Housing Partnerships, Tax Credit and Other Investments, Net to the Consolidated Financial Statements for additional information.