Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Issued Amount	$ 230,061
Carrying Value	185,449	[1]
Estimated Fair Value [Member]
Issued Amount	134,024
Carrying Value	82,905	[1]
Amortized Cost [Member]
Issued Amount	96,037
Carrying Value	102,544	[1]
Umpqua Statutory Trust II [Member] | Estimated Fair Value [Member]
Issue Date	October 2002
Issued Amount	20,619
Carrying Value	14,166	[1]
Rate	Floating	[2],[3]
Effective Rate	5.50%	[4]
Maturity Date	October 2032
Redemption Date	October 2007
Interest Rate Adjustment	3.35%
Umpqua Statutory Trust III [Member] | Estimated Fair Value [Member]
Issue Date	October 2002
Issued Amount	30,928
Carrying Value	21,476	[1]
Rate	Floating	[2],[5]
Effective Rate	5.62%	[4]
Maturity Date	November 2032
Redemption Date	November 2007
Umpqua Statutory Trust IV [Member] | Estimated Fair Value [Member]
Issue Date	December 2003
Issued Amount	10,310
Carrying Value	6,641	[1]
Rate	Floating	[2],[6]
Effective Rate	5.05%	[4]
Maturity Date	January 2034
Redemption Date	January 2009
Umpqua Statutory Trust V [Member] | Estimated Fair Value [Member]
Issue Date	December 2003
Issued Amount	10,310
Carrying Value	6,625	[1]
Rate	Floating	[2],[6]
Effective Rate	5.31%	[4]
Maturity Date	March 2034
Redemption Date	March 2009
Umpqua Master Trust I [Member] | Estimated Fair Value [Member]
Issue Date	August 2007
Issued Amount	41,238
Carrying Value	21,134	[1]
Rate	Floating	[2],[7]
Effective Rate	3.70%	[4]
Maturity Date	September 2037
Redemption Date	September 2012
Interest Rate Adjustment	1.35%
Umpqua Master Trust IB [Member] | Estimated Fair Value [Member]
Issue Date	September 2007
Issued Amount	20,619
Carrying Value	12,863	[1]
Rate	Floating	[2],[8]
Effective Rate	5.28%	[4]
Maturity Date	December 2037
Redemption Date	December 2012
Interest Rate Adjustment	2.75%
HB Capital Trust I [Member] | Amortized Cost [Member]
Issue Date	March 2000
Issued Amount	5,310
Carrying Value	6,329	[1]
Rate	10.875	[2]
Effective Rate	8.24%	[4]
Maturity Date	March 2030
Redemption Date	March 2010
Humboldt Bancorp Statutory Trust I [Member] | Amortized Cost [Member]
Issue Date	February 2001
Issued Amount	5,155
Carrying Value	5,897	[1]
Rate	10.200	[2]
Effective Rate	8.26%	[4]
Maturity Date	February 2031
Redemption Date	February 2011
Humboldt Bancorp Statutory Trust II [Member] | Amortized Cost [Member]
Issue Date	December 2001
Issued Amount	10,310
Carrying Value	11,378	[1]
Rate	Floating	[2],[9]
Effective Rate	3.29%	[4]
Maturity Date	December 2031
Redemption Date	December 2006
Humboldt Bancorp Statutory Trust III [Member] | Amortized Cost [Member]
Issue Date	September 2003
Issued Amount	27,836
Carrying Value	30,605	[1]
Rate	Floating	[10],[2]
Effective Rate	2.76%	[4]
Maturity Date	September 2033
Redemption Date	September 2008
Interest Rate Adjustment	2.95%
CIB Capital Trust [Member] | Amortized Cost [Member]
Issue Date	November 2002
Issued Amount	10,310
Carrying Value	11,219	[1]
Rate	Floating	[2],[5]
Effective Rate	3.20%	[4]
Maturity Date	November 2032
Redemption Date	November 2007
Western Sierra Statutory Trust I [Member] | Amortized Cost [Member]
Issue Date	July 2001
Issued Amount	6,186
Carrying Value	6,186	[1]
Rate	Floating	[11],[2]
Effective Rate	4.01%	[4]
Maturity Date	July 2031
Redemption Date	July 2006
Interest Rate Adjustment	3.58%
Western Sierra Statutory Trust II [Member] | Amortized Cost [Member]
Issue Date	December 2001
Issued Amount	10,310
Carrying Value	10,310	[1]
Rate	Floating	[2],[9]
Effective Rate	4.15%	[4]
Maturity Date	December 2031
Redemption Date	December 2006
Western Sierra Statutory Trust III [Member] | Amortized Cost [Member]
Issue Date	September 2003
Issued Amount	10,310
Carrying Value	10,310	[1]
Rate	Floating	[12],[2]
Effective Rate	3.30%	[4]
Maturity Date	September 2033
Redemption Date	September 2008
Western Sierra Statutory Trust IV [Member] | Amortized Cost [Member]
Issue Date	September 2003
Issued Amount	10,310
Carrying Value	$ 10,310	[1]
Rate	Floating	[12],[2]
Effective Rate	3.30%	[4]
Maturity Date	September 2033
Redemption Date	September 2008
Umpqua Statutory Trust III [Member] | CIB Capital Trust [Member] | Estimated Fair Value [Member]
Interest Rate Adjustment	3.45%
Umpqua Statutory Trust IV [Member] | Umpqua Statutory Trust V [Member] | Estimated Fair Value [Member]
Interest Rate Adjustment	2.85%
Western Sierra Statutory Trust II [Member] | Humboldt Bancorp Statutory Trust I [Member] | Amortized Cost [Member]
Interest Rate Adjustment	3.60%
Western Sierra Statutory Trust III [Member] | Western Sierra Statutory Trust IV [Member] | Amortized Cost [Member]
Interest Rate Adjustment	2.90%

[1] Includes purchase accounting adjustments, net of accumulated amortization, for junior subordinated debentures assumed in connection with previous mergers as well as fair value adjustments related to trusts recorded at fair value.

[2] Contractual interest rate of junior subordinated debentures.

[3] Rate based on LIBOR plus 3.35%, adjusted quarterly.

[4] Effective interest rate based upon the carrying value as of December 2011.

[5] Rate based on LIBOR plus 3.45%, adjusted quarterly.

[6] Rate based on LIBOR plus 2.85%, adjusted quarterly.

[7] Rate based on LIBOR plus 1.35%, adjusted quarterly.

[8] Rate based on LIBOR plus 2.75%, adjusted quarterly.

[9] Rate based on LIBOR plus 3.60%, adjusted quarterly.

[10] Rate based on LIBOR plus 2.95%, adjusted quarterly.

[11] Rate based on LIBOR plus 3.58%, adjusted quarterly.

[12] Rate based on LIBOR plus 2.90%, adjusted quarterly.