CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Common Stock	Additional Paid In Capital Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss) Income, Net of Tax
BALANCE at Dec. 31, 2013	[1]	$ 2,366,373		$ 163	$ 1,571,670	$ 1,362,278	$ (537,279)	$ (30,459)
Increase (Decrease) in Stockholders' Equity
Net income	[1]	250,376				250,376
Other comprehensive loss		28,031						28,031
Stock compensation costs		10,382			10,382
Tax benefit from stock compensation plans, net		3,916			3,916
Issuance of 414,623 and 398,012 shares of common stock pursuant to various stock compensation plans and agreements for the period ended September 30, 2015 and 2014, respectively		1,249			1,249
Issuance of 17,840 and 18,909 shares of common stock pursuant to Director retainer fee for the period ended September 30, 2015 and 2014, respectively		630			630
Cancellation of 17,337 shares of common stock due to forfeitures of issued restricted stock		0			323		(323)
144,738 and 208,440 shares of restricted stock surrendered due to employee tax liability for the period ended September 30, 2015 and 2014, respectively		(7,532)					(7,532)
Common stock dividends		(77,978)				(77,978)
Issuance of 5,583,093 shares pursuant to MetroCorp Bancshares, Inc. acquisition		190,830			73,044		117,786
Warrant acquired pursuant to MetroCorp Bancshares, Inc. acquisition		4,855			4,855
BALANCE at Sep. 30, 2014	[1]	2,771,132		163	1,666,069	1,534,676	(427,348)	(2,428)
BALANCE at Dec. 31, 2014	[1]	2,856,111		164	1,677,767	1,604,141	(430,198)	4,237
Increase (Decrease) in Stockholders' Equity
Net income		292,872	[1]			292,872
Other comprehensive loss		(2,407)						(2,407)
Stock compensation costs		11,702			11,702
Tax benefit from stock compensation plans, net		3,227			3,227
Issuance of 414,623 and 398,012 shares of common stock pursuant to various stock compensation plans and agreements for the period ended September 30, 2015 and 2014, respectively		1,769			1,769
Issuance of 17,840 and 18,909 shares of common stock pursuant to Director retainer fee for the period ended September 30, 2015 and 2014, respectively		800			800
144,738 and 208,440 shares of restricted stock surrendered due to employee tax liability for the period ended September 30, 2015 and 2014, respectively		(5,859)					(5,859)
Common stock dividends		(87,100)				(87,100)
BALANCE at Sep. 30, 2015		$ 3,071,115	[1]	$ 164	$ 1,695,265	$ 1,809,913	$ (436,057)	$ 1,830

[1] Prior periods were 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. See Note 10 — Investments in Qualified Affordable Housing Partnerships, Tax Credit and Other Investments, Net to the Consolidated Financial Statements for additional information.