CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified		Common Stock	Additional Paid In Capital Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss), Net of Tax	Total
BALANCE at Dec. 31, 2013	[1]	$ 163	$ 1,571,670	$ 1,362,278	$ (537,279)	$ (30,459)	$ 2,366,373
Increase (Decrease) in Stockholders' Equity
Net income	[1]			74,171			74,171
Other comprehensive income						13,422	13,422
Stock compensation costs			3,180				3,180
Tax benefit from stock compensation plans, net			3,708				3,708
Issuance of 379,191 and 356,187 shares of common stock pursuant to various stock compensation plans and agreements for the period ended March 31, 2015 and 2014, respectively			283				283
Cancellation of 7,233 shares of common stock due to forfeitures of issued restricted stock for the period ended March 31, 2014			127		(127)
140,871 and 195,291 shares of restricted stock surrendered due to employee tax liability for the period ended March 31, 2015 and 2014, respectively					(7,074)		(7,074)
Common stock dividends				(25,950)			(25,950)
Issuance of 5,583,093 shares pursuant to MetroCorp acquisition			73,044		117,786		190,830
Warrant acquired pursuant to MetroCorp acquisition			4,855				4,855
BALANCE at Mar. 31, 2014	[1]	163	1,656,867	1,410,499	(426,694)	(17,037)	2,623,798
BALANCE at Dec. 31, 2014	[1]	164	1,677,767	1,604,141	(430,198)	4,237	2,856,111
Increase (Decrease) in Stockholders' Equity
Net income				100,027			100,027
Other comprehensive income						9,318	9,318
Stock compensation costs			3,954				3,954
Tax benefit from stock compensation plans, net			3,145				3,145
Issuance of 379,191 and 356,187 shares of common stock pursuant to various stock compensation plans and agreements for the period ended March 31, 2015 and 2014, respectively			833				833
140,871 and 195,291 shares of restricted stock surrendered due to employee tax liability for the period ended March 31, 2015 and 2014, respectively					(5,691)		(5,691)
Common stock dividends				(28,934)			(28,934)
BALANCE at Mar. 31, 2015		$ 164	$ 1,685,699	$ 1,675,234	$ (435,889)	$ 13,555	$ 2,938,763

[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 Standard Update ("ASU") 2014-01. See Note 10 of the Notes to Consolidated Financial Statements for additional information.