SELECTED QUARTERLY FINANCIAL DATA (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 29, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SELECTED QUARTERLY FINANCIAL DATA (Unaudited)
Interest income	$ 73,702	$ 75,123	$ 72,890	$ 74,400	$ 70,913	$ 72,518	$ 77,196	$ 74,657	$ 296,115	$ 295,284	$ 290,284
Interest expense	(4,099)	(4,352)	(4,477)	(6,720)	(7,140)	(8,077)	(8,507)	(8,919)	(19,648)	(32,643)	(40,957)
Net interest income	69,603	70,771	68,413	67,680	63,773	64,441	68,689	65,738	276,467	262,641	249,327
Negative provision (provision) for credit losses:
Non-covered loans		2,000		10,000			(5,500)	(7,800)	9,750	(10,505)
Covered loans	4,333	141	271	(3,926)	(4,122)	(348)	(5,890)	(2,910)	819	(13,270)	(33,500)
Total negative provision for credit losses	4,333	2,141	271	6,074	(4,122)	(348)	(11,390)	(10,710)	12,819	(26,570)	(212,492)
FDIC loss sharing (expense) income, net	(6,022)	(367)	(102)	(3,579)	2,667	963	5,316	(1,170)	(10,070)	7,776	22,784
Gain on sale of securities	1,239								1,239
Other-than-temporary-impairment losses on covered securities			(1,115)						(1,115)		(874)
Other noninterest income	6,840	6,049	6,088	6,841	5,587	6,180	5,924	5,959
Total noninterest income	2,057	5,682	4,871	3,262	8,254	7,143	11,240	4,789	15,872	31,426	43,238
Non-covered OREO expense, net	(316)	(1,883)	(130)	(1,821)	(1,714)	(2,293)	(2,300)	(703)	(4,150)	(7,010)	(12,310)
Covered OREO expense, net	461	(4,290)	(2,130)	(822)	(226)	(4,813)	(1,205)	2,578	(6,781)	(3,666)	(2,460)
Acquisition and integration costs	(1,092)	(2,101)	(871)	(25)	(600)				(4,089)	(600)	(732)
Debt termination expense				(22,598)					(22,598)		(2,660)
Other noninterest expense	(42,578)	(43,383)	(44,454)	(43,629)	(40,929)	(41,481)	(43,033)	(43,274)
Total noninterest expense	(43,525)	(51,657)	(47,585)	(68,895)	(43,469)	(48,587)	(46,538)	(41,399)	(211,662)	(179,993)	(188,803)
Earnings (loss) before income taxes	32,468	26,937	25,970	8,121	24,436	22,649	22,001	18,418	93,496	87,504	(108,730)
Income tax (expense) benefit	(12,576)	(10,849)	(10,413)	(2,857)	(10,553)	(9,345)	(9,160)	(7,742)	(36,695)	(36,800)	46,714
NET EARNINGS (LOSS)	$ 19,892	$ 16,088	$ 15,557	$ 5,264	$ 13,883	$ 13,304	$ 12,841	$ 10,676	$ 56,801	$ 50,704	$ (62,016)
Earnings per share:
Basic (in dollars per share)	$ 0.54	$ 0.43	$ 0.42	$ 0.14	$ 0.38	$ 0.36	$ 0.35	$ 0.29	$ 1.54	$ 1.37	$ (1.77)
Diluted (in dollars per share)	$ 0.54	$ 0.43	$ 0.42	$ 0.14	$ 0.38	$ 0.36	$ 0.35	$ 0.29	$ 1.54	$ 1.37	$ (1.77)