Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012
Junior Subordinated Debentures [Line Items]
Issued and Outstanding Amount	$ 230,061
Carrying Value	185,916	[1]
Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issued and Outstanding Amount	134,024
Carrying Value	83,453	[1]
Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issued and Outstanding Amount	96,037
Carrying Value	102,463	[1]
Umpqua Statutory Trust II [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	October 2002
Issued and Outstanding Amount	20,619
Carrying Value	14,246	[1]
Rate	Floating(4)	[2],[3]
Effective Rate	5.65%	[4]
Maturity Date	October 2032
Redemption Date	October 2007
Umpqua Statutory Trust II [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	3.35%
Umpqua Statutory Trust III [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	October 2002
Issued and Outstanding Amount	30,928
Carrying Value	21,590	[1]
Rate	Floating(5)	[2],[5]
Effective Rate	5.66%	[4]
Maturity Date	November 2032
Redemption Date	November 2007
Umpqua Statutory Trust III [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	3.45%
Umpqua Statutory Trust IV [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	December 2003
Issued and Outstanding Amount	10,310
Carrying Value	6,684	[1]
Rate	Floating(6)	[2],[6]
Effective Rate	5.28%	[4]
Maturity Date	January 2034
Redemption Date	January 2009
Umpqua Statutory Trust IV [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	2.85%
Umpqua Statutory Trust V [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	December 2003
Issued and Outstanding Amount	10,310
Carrying Value	6,665	[1]
Rate	Floating(6)	[2]
Effective Rate	5.14%	[4]
Maturity Date	March 2034
Redemption Date	March 2009
Umpqua Master Trust I [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	August 2007
Issued and Outstanding Amount	41,238
Carrying Value	21,329	[1]
Rate	Floating(7)	[2],[7]
Effective Rate	3.53%	[4]
Maturity Date	September 2037
Redemption Date	September 2012
Umpqua Master Trust I [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	1.35%
Umpqua Master Trust IB [Member] | Estimated Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	September 2007
Issued and Outstanding Amount	20,619
Carrying Value	12,939	[1]
Rate	Floating(8)	[2],[8]
Effective Rate	5.14%	[4]
Maturity Date	December 2037
Redemption Date	December 2012
Umpqua Master Trust IB [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	2.75%
HB Capital Trust I [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	March 2000
Issued and Outstanding Amount	5,310
Carrying Value	6,315	[1]
Rate	10.875%	[2]
Effective Rate	8.26%	[4]
Maturity Date	March 2030
Redemption Date	March 2010
Humboldt Bancorp Statutory Trust I [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	February 2001
Issued and Outstanding Amount	5,155
Carrying Value	5,887	[1]
Rate	10.200%	[2]
Effective Rate	8.27%	[4]
Maturity Date	February 2031
Redemption Date	February 2011
Humboldt Bancorp Statutory Trust II [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	3.60%
Humboldt Bancorp Statutory Trust II [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	December 2001
Issued and Outstanding Amount	10,310
Carrying Value	11,365	[1]
Rate	Floating(9)	[2],[9]
Effective Rate	3.22%	[4]
Maturity Date	December 2031
Redemption Date	December 2006
Humboldt Bancorp Statutory Trust III [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	2.95%
Humboldt Bancorp Statutory Trust III [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	September 2003
Issued and Outstanding Amount	27,836
Carrying Value	30,572	[1]
Rate	Floating(10)	[10],[2]
Effective Rate	2.69%	[4]
Maturity Date	September 2033
Redemption Date	September 2008
CIB Capital Trust [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	November 2002
Issued and Outstanding Amount	10,310
Carrying Value	11,208	[1]
Rate	Floating(5)	[2],[5]
Effective Rate	3.24%	[4]
Maturity Date	November 2032
Redemption Date	November 2007
Western Sierra Statutory Trust I [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	3.58%
Western Sierra Statutory Trust I [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	July 2001
Issued and Outstanding Amount	6,186
Carrying Value	6,186	[1]
Rate	Floating(11)	[11],[2]
Effective Rate	4.12%	[4]
Maturity Date	July 2031
Redemption Date	July 2006
Western Sierra Statutory Trust II [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	December 2001
Issued and Outstanding Amount	10,310
Carrying Value	10,310	[1]
Rate	Floating(9)	[2],[9]
Effective Rate	4.07%	[4]
Maturity Date	December 2031
Redemption Date	December 2006
Western Sierra Statutory Trust III [Member] | Subordinated Debt Carrying Value [Member]
Junior Subordinated Debentures [Line Items]
Interest Rate Adjustment	2.90%
Western Sierra Statutory Trust III [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	September 2003
Issued and Outstanding Amount	10,310
Carrying Value	10,310	[1]
Rate	Floating(12)	[12],[2]
Effective Rate	3.47%	[4]
Maturity Date	September 2033
Redemption Date	September 2008
Western Sierra Statutory Trust IV [Member] | Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issue Date	September 2003
Issued and Outstanding Amount	10,310
Carrying Value	$ 10,310	[1]
Rate	Floating(12)	[12],[2]
Effective Rate	3.47%	[4]
Maturity Date	September 2033
Redemption Date	September 2008

[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 March 2012.

[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.