Business Combinations (Pro Forma Results of Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	$ 106,809		$ 102,040		$ 294,891		$ 305,407
Provision for non-covered loan and lease losses	3,008		7,078		12,989		16,883
(RECAPTURE OF) PROVISION FOR COVERED LOAN LOSSES	(1,904)		2,927		(4,744)		4,302
Non-interest income	26,144		33,679		94,656		89,842
Non-interest expense	95,604		86,974		269,297		261,606
Income before income taxes	36,245		38,740		112,005		112,458
Provision for income taxes	12,768		13,587		38,914		38,525
Net income	23,477		25,153		73,091		73,933		101,891
Dividends and undistributed earnings allocated to participating securities	196	[1]	170	[1]	576	[1]	499	[1]
Net earnings available to common shareholders	23,281		24,983		72,515		73,434
Earnings per share:
Basic (in usd per share)	$ 0.21		$ 0.22		$ 0.65		$ 0.66
Diluted (in usd per share)	$ 0.21		$ 0.22		$ 0.65		$ 0.65
Average shares outstanding:
Basic (in shares)	111,912		111,899		111,934		111,928
Diluted (in shares)	112,195		112,151		112,154		112,159
Merger related expenses	4,856		85		7,197		338
Pro Forma [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	105,688		115,237		318,904		344,813
Provision for non-covered loan and lease losses	4,532		10,955		20,826		25,511
(RECAPTURE OF) PROVISION FOR COVERED LOAN LOSSES	(1,904)		2,927		(4,744)		4,302
Non-interest income	26,144		34,428		95,968		92,593
Non-interest expense	95,130		90,507		275,783		272,241
Income before income taxes	34,074		45,276		123,007		135,352
Provision for income taxes	11,900		16,056		43,039		47,257
Net income	22,174		29,220		79,968		88,095
Dividends and undistributed earnings allocated to participating securities	248		197		686		595
Net earnings available to common shareholders	21,926		29,023		79,282		87,500
Earnings per share:
Basic (in usd per share)	$ 0.20		$ 0.26		$ 0.71		$ 0.78
Diluted (in usd per share)	$ 0.20		$ 0.26		$ 0.71		$ 0.78
Average shares outstanding:
Basic (in shares)	111,912		111,899		111,934		111,928
Diluted (in shares)	112,195		112,151		112,154		112,159
Acquisition-related Costs [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	(1,121)	[2]	1,167	[3]	(1,513)	[3]	3,509	[3]
Provision for non-covered loan and lease losses	1,524	[4]	1,361	[4]	4,565	[4]	415	[4]
Non-interest income	0		0		0		0
Non-interest expense	(474)	[5]	(303)	[6]	(1,802)	[7]	(910)	[6]
Income before income taxes	(2,171)		109		(4,276)		4,004
Provision for income taxes	(868)	[8]	44	[8]	(1,710)	[8]	1,601	[8]
Net income	(1,303)		65		(2,566)		2,403
Dividends and undistributed earnings allocated to participating securities	52		27		110		96
Net earnings available to common shareholders	(1,355)		38		(2,676)		2,307
Average shares outstanding:
Income tax effect of pro forma adjustments	40.00%		40.00%		40.00%		40.00%
UmpquaFinPacAcquisition [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	92,311		102,040		280,393		305,407
Provision for non-covered loan and lease losses	1,228		7,078		11,209		16,883
(RECAPTURE OF) PROVISION FOR COVERED LOAN LOSSES	(1,904)		2,927		(4,744)		4,302
Non-interest income	25,815		33,679		94,327		89,842
Non-interest expense	92,108		86,974		265,801		261,606
Income before income taxes	26,694		38,740		102,454		112,458
Provision for income taxes	9,169		13,587		35,315		38,525
Net income	17,525		25,153		67,139		73,933
Dividends and undistributed earnings allocated to participating securities	196		170		576		499
Net earnings available to common shareholders	17,329		24,983		66,563		73,434
Earnings per share:
Basic (in usd per share)	$ 0.15		$ 0.22		$ 0.59		$ 0.66
Diluted (in usd per share)	$ 0.15		$ 0.22		$ 0.59		$ 0.65
Average shares outstanding:
Basic (in shares)	111,912		111,899		111,934		111,928
Diluted (in shares)	112,195		112,151		112,154		112,159
Financial Pacific Holding Corp [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	14,498	[9]	12,030	[10]	40,024	[11]	35,897	[12]
Provision for non-covered loan and lease losses	1,780	[9]	2,516	[10]	5,052	[11]	8,213	[12]
(RECAPTURE OF) PROVISION FOR COVERED LOAN LOSSES	0	[9]	0	[10]	0	[11]	0	[12]
Non-interest income	329	[9]	749	[10]	1,641	[11]	2,751	[12]
Non-interest expense	3,496	[9]	3,836	[10]	11,784	[11]	11,545	[12]
Income before income taxes	9,551	[9]	6,427	[10]	24,829	[11]	18,890	[12]
Provision for income taxes	3,599	[9]	2,425	[10]	9,434	[11]	7,131	[12]
Net income	5,952	[9]	4,002	[10]	15,395	[11]	11,759	[12]
Dividends and undistributed earnings allocated to participating securities	0	[9]	0	[10]	0	[11]	0	[12]
Net earnings available to common shareholders	5,952	[9]	4,002	[10]	15,395	[11]	11,759	[12]
Average shares outstanding:
Merger related expenses	$ 629				$ 1,424

[1] Represents dividends paid and undistributed earnings allocated to nonvested restricted stock awards.

[2] Consists of change in yields due to fair value adjustments.

[3] Consists of interest expense benefit of FinPac utilizing Bank funding, and change in yields due to fair value adjustments.

[4] Consists of adjustment to FinPac provision for credit losses due to purchase accounting adjustments.

[5] Consists of merger related expenses of $629,000 at the Bank, additional expense related to restricted stock, and FinPac amortization of intangible assets, director compensation and travel, and management fees.

[6] Consists of additional expense related to restricted stock, and FinPac amortization of intangible assets, director compensation and travel, and management fees.

[7] Consists of merger related expenses of $1.4 million at the Bank, additional expense related to restricted stock, and FinPac amortization of intangible assets, director compensation and travel, and management fees.

[8] Income tax effect of pro forma adjustments at 40%.

[9] FinPac amounts represent results from July 1, 2013 to September 30, 2013.

[10] FinPac amounts represent results from July 1, 2012 to September 30, 2012.

[11] FinPac amounts represent results from January 1, 2013 to September 30, 2013.

[12] FinPac amounts represent results from January 1, 2012 to September 30, 2012.