COVERED ASSETS AND FDIC INDEMNIFICATION ASSET, FDIC Indemnification Asset and FDIC Receivable (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010		Dec. 31, 2010
FDIC indemnification asset activity [Rollforward]
Balance at beginning of period	$ 717,260,000		$ 980,950,000		$ 792,133,000		$ 1,091,814,000
Addition due to WFIB acquisition	0		41,131,000		0		41,131,000
(Amortization) Accretion	(15,432,000)		10,624,000		(33,709,000)		22,092,000
Reductions	(64,293,000)	[1],[2]	(85,694,000)	[1],[2]	(120,889,000)	[1],[2]	(208,026,000)	[1],[2]
Balance at end of period	637,535,000		947,011,000		637,535,000		947,011,000
Amount of chargeoffs recoverable from the FDIC	42,800,000		56,100,000		74,300,000		118,000,000
FDIC Receivable [Abstract]
FDIC loss sharing receivable	$ 79,800,000				$ 79,800,000				$ 55,500,000
Percentage of any reimbursable expense recorded as noninterest income (in hundredths)	80.00%				80.00%
Percentage of reimbursable expenses recorded as non-interest expense (in hundredths)	100.00%				100.00%
Percentage of actual expense paid by the Company (in hundredths)	20.00%				20.00%

[1] For the three and six months ended June 30, 2011, the reduction amounts of $64.3 million and $120.9 million, respectively, include charge-offs, of which $42.8 million and $74.3 million, respectively, of these charge-offs are recoverable from the FDIC and recorded in other assets. For the three and six months ended June 30, 2010, the reduction amounts of $85.7 million and $208.0 million, respectively, also include charge-offs, of which $56.1 million and $118.0 million, respectively, is recoverable from the FDIC and recorded in other assets.

[2] Reductions relate to higher cash flows received from principal amortization, partial prepayments, loan payoffs and loan sales.