FDIC-ASSISTED TRANSACTIONS (Schedule of Assets Acquired and Liabilities Assumed in CCB Acquisition) (Details) (USD $) In Thousands, unless otherwise specified							3 Months Ended			0 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008	Sep. 30, 2011 Colorado Capital Bank [Member]	Jul. 08, 2011 Colorado Capital Bank [Member]	Jul. 08, 2011 As Recorded By CCB [Member] Colorado Capital Bank [Member]	Jul. 08, 2011 Fair Value Adjustments [Member] Colorado Capital Bank [Member]		Jul. 08, 2011 Subsequent Acquisition Date Adjustments [Member] Colorado Capital Bank [Member]	Jul. 08, 2011 As Recorded By FCB [Member] Colorado Capital Bank [Member]
Business Acquisition [Line Items]
Cash and due from banks	$ 590,801		$ 460,178						$ 74,736	$ 0		$ 0	$ 74,736
Investment securities available for sale	4,056,423		4,510,076						40,187	0		0	40,187
Loans covered by loss share agreements	2,362,152	[1]	2,007,452	[1]				320,789	538,369	(216,207)	[2]	(1,373)	320,789
Other real estate owned covered by loss share agreements	50,399		52,842						14,853	(7,699)	[3]	3,058	10,212
Income earned not collected	42,216		83,644						1,720	0		0	1,720
Receivable from FDIC for loss share agreements	539,511		623,261		249,842	0			0	157,600	[4]	(2,530)	155,070
Core deposit intangible									0	984	[5]	0	984
Other assets	286,430		258,524						3,296	0		0	3,296
Total assets acquired	20,881,493		20,806,659						673,161	(65,322)		(845)	606,994
Deposits: Noninterest-bearing	4,331,706		3,976,366						35,862	0		0	35,862
Deposits: Interest-bearing	13,245,568		13,658,900						571,251	(612)	[6]	0	570,639
Total deposits	17,577,274		17,635,266						607,113	(612)		0	606,501
Short-term borrowings	615,222		546,597						15,008	204	[7]	0	15,212
Other liabilities	140,270		81,885						438	0		0	438
Total liabilities assumed	19,020,365		19,073,697						622,559	(408)		0	622,151
Excess of assets acquired over liabilities									50,602
Aggregate fair value adjustments										(64,914)		(845)
Cash received from the FDIC													102,100
Gain on acquisition of CCB							$ 86,943						$ 86,943

[1] Covered loans are acquired loans subject to loss share agreements with the FDIC.

[2] Adjustment reflects the fair value adjustments based on FCB’s evaluation of the acquired loan portfolio.

[3] Adjustment reflects the estimated OREO losses based on FCB’s evaluation of the acquired OREO.

[4] Adjustment reflects the estimated fair value of payments FCB will receive from the FDIC under the loss share agreements.

[5] Adjustment reflects the estimated value of intangible assets, which includes core deposit intangibles.

[6] Adjustment reflects the fair value of deposits assumed based on FCB's evaluation of the term deposits assumed.

[7] Adjustment reflects the amount of the prepayment penalty assessed on early payoff of long-term obligations.