FAIR VALUE (Details) (USD $)	3 Months Ended		9 Months Ended										3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Estimated Fair Value [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Estimated Fair Value [Member]	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Estimated Fair Value [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Estimated Fair Value [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Estimated Fair Value [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Estimated Fair Value [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Total Gains (Losses) [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Total Gains (Losses) [Member]		Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Total Gains (Losses) [Member]		Sep. 30, 2010 Fair Value, Measurements, Nonrecurring [Member] Total Gains (Losses) [Member]
Investment securities available-for-sale: [Abstract]
U.S. Treasury securities					$ 20,761,000	$ 20,454,000	$ 20,761,000	$ 20,454,000	$ 0	$ 0	$ 0	$ 0
U.S. Government agency and U.S. Government sponsored enterprise debt securities					642,951,000	1,333,465,000	0	0	642,951,000	1,333,465,000	0	0
U.S. Government agency and U.S. Government sponsored enterprise mortgage-backed securities: [Abstract]
Commercial mortgage-backed securities					16,823,000	19,132,000	0	0	16,823,000	19,132,000	0	0
Residential mortgage-backed securities					1,093,829,000	306,714,000	0	0	1,093,829,000	306,714,000	0	0
Municipal securities					77,466,000	0	0	0	77,466,000	0	0	0
Other residential mortgage-backed securities: [Abstract]
Investment grade					0	0	0	0	0	0	0	0
Non-investment grade					0	6,254,000	0	0	0	0	0	6,254,000
Corporate debt securities: [Abstract]
Investment grade					1,403,432,000	1,056,867,000	0	0	1,403,432,000	1,056,867,000	0	0
Non-investment grade					14,195,000	38,730,000	0	0	11,840,000	35,957,000	2,355,000	2,773,000
Other securities					10,135,000	94,325,000	0	0	10,135,000	94,325,000	0	0
Total investment securities available-for-sale					3,279,592,000	2,875,941,000	20,761,000	20,454,000	3,256,476,000	2,846,460,000	2,355,000	9,027,000
Equity swap agreements					200,000	206,000	0	0	200,000	206,000	0	0
Foreign exchange options					4,392,000	5,084,000	0	0	4,392,000	5,084,000	0	0
Interest rate swaps					17,791,000	13,000	0	0	17,791,000	13,000	0	0
Derivative liabilities					(20,206,000)	(3,463,000)	0	0	(17,237,000)	(14,000)	(2,969,000)	(3,449,000)
Non-covered impaired loans: [Abstract]
Total residential													9,637,000		2,694,000		12,533,000		5,953,000		0		0		0		0		0		0		0		0		9,637,000		2,694,000		12,533,000		5,953,000		(3,142,000)		(772,000)		(3,727,000)		(2,234,000)
Total commercial real estate													40,997,000		41,212,000		44,840,000		74,630,000		0		0		0		0		0		0		0		0		40,997,000		41,212,000		44,840,000		74,630,000		(16,645,000)		(16,046,000)		(34,192,000)		(36,230,000)
Total commercial and industrial													4,405,000		7,830,000		5,513,000		7,925,000		0		0		0		0		0		0		0		0		4,405,000		7,830,000		5,513,000		7,925,000		(6,328,000)		(3,053,000)		(9,915,000)		(4,836,000)
Total consumer													315,000		167,000		359,000		166,000		0		0		0		0		0		0		0		0		315,000		167,000		359,000		166,000		(265,000)		96,000		(443,000)		(245,000)
Total non-covered impaired loans													55,354,000		51,903,000		63,245,000		88,674,000		0		0		0		0		0		0		0		0		55,354,000		51,903,000		63,245,000		88,674,000		(26,380,000)		(19,775,000)		(48,277,000)		(43,545,000)
Mortgage servicing assets (single-family, multifamily and commercial)													12,495,000		15,973,000		12,495,000		15,973,000		0		0		0		0		0		0		0		0		12,495,000		15,973,000		12,495,000		15,973,000		(212,000)		(284,000)		(675,000)		(348,000)
Non-covered OREO			21,200,000										36,000		2,574,000		13,692,000		4,101,000		0		0		0		0		36,000		2,574,000		13,692,000		4,101,000		0		0		0		0		(17,000)		(1,099,000)		(1,529,000)		(4,012,000)
Covered OREO			87,300,000										18,068,000	[1]	27,205,000	[1]	110,133,000	[2]	57,234,000	[2]	0	[1]	0	[1]	0	[2]	0	[2]	18,068,000	[1]	27,205,000	[1]	110,133,000	[2]	57,234,000	[2]	0	[1]	0	[1]	0	[2]	0	[2]	(3,252,000)	[1]	(6,569,000)	[1]	(18,655,000)	[2]	(32,496,000)	[2]
Loans held for sale													2,714,000		359,000		2,714,000		3,737,000		0		0		0		0		0		0		0		0		2,714,000		359,000		2,714,000		3,737,000		(260,000)		(228,000)		(260,000)		(2,059,000)
FDIC percentage of reimbursement under shared loss agreements (in hundredths)	80.00%	80.00%	80.00%	80.00%
Percentage of company's liability for losses under shared loss agreements (in hundredths)	20.00%	20.00%	20.00%	20.00%
Company's liability for losses under shared loss agreements	650,000	1,300,000	3,700,000	6,500,000
Total eligible losses subject to shared loss agreements	$ 3,300,000	$ 6,600,000	$ 18,700,000	$ 32,500,000

[1] Covered OREO results from the WFIB and UCB FDIC-assisted acquisitions for which the Company entered into shared-loss agreements with the FDIC whereby the FDIC will reimburse the Company for 80% of eligible losses. As such, the Company's liability for losses is 20% of the $3.3 million in losses, or $650 thousand, and 20% of the $6.6 million in losses, or $1.3 million, for the three months ended September 30, 2011 and 2010, respectively.

[2] Covered OREO results from the WFIB and UCB FDIC-assisted acquisitions for which the Company entered into shared-loss agreements with the FDIC whereby the FDIC will reimburse the Company for 80% of eligible losses. As such, the Company's liability for losses is 20% of the $18.7 million in losses, or $3.7 million, and 20% of the $32.5 million in losses, or $6.5 million, for the nine months ended September 30, 2011 and 2010, respectively.