Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 475,427
AT AMORTIZED COST	101,576	101,899
Carrying Value	350,870
Junior Subordinated Debt, at Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	379,390
AT FAIR VALUE	249,294
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	October 2002
Issued Amount	20,619
AT FAIR VALUE	15,108
Rate	LIBOR
Basis spread on LIBOR	3.35%
Effective Rate	4.89%
Maturity Date of Trust	October 2032
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	October 2002
Issued Amount	30,928
AT FAIR VALUE	22,852
Rate	LIBOR
Basis spread on LIBOR	3.45%
Effective Rate	4.98%
Maturity Date of Trust	November 2032
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	December 2003
Issued Amount	10,310
AT FAIR VALUE	7,147
Rate	LIBOR
Basis spread on LIBOR	2.85%
Effective Rate	4.44%
Maturity Date of Trust	January 2034
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust V [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	December 2003
Issued Amount	10,310
AT FAIR VALUE	7,124
Rate	LIBOR
Basis spread on LIBOR	2.85%
Effective Rate	4.48%
Maturity Date of Trust	March 2034
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Master Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	August 2007
Issued Amount	41,238
AT FAIR VALUE	23,480
Rate	LIBOR
Basis spread on LIBOR	1.35%
Effective Rate	2.79%
Maturity Date of Trust	September 2037
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Master Trust IB [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	September 2007
Issued Amount	20,619
AT FAIR VALUE	13,761
Rate	LIBOR
Basis spread on LIBOR	2.75%
Effective Rate	4.48%
Maturity Date of Trust	December 2037
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	April 2003
Issued Amount	14,433
AT FAIR VALUE	11,121
Rate	LIBOR
Basis spread on LIBOR	3.25%
Effective Rate	4.53%
Maturity Date of Trust	April 2033
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	May 2003
Issued Amount	10,310
AT FAIR VALUE	7,858
Rate	LIBOR
Basis spread on LIBOR	3.15%
Effective Rate	4.44%
Maturity Date of Trust	May 2033
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Statutory Trust V [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	May 2003
Issued Amount	20,619
AT FAIR VALUE	15,776
Rate	LIBOR
Basis spread on LIBOR	3.25%
Effective Rate	4.55%
Maturity Date of Trust	June 2033
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VI [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	June 2003
Issued Amount	10,310
AT FAIR VALUE	7,836
Rate	LIBOR
Basis spread on LIBOR	3.20%
Effective Rate	4.52%
Maturity Date of Trust	September 2033
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VII [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	June 2006
Issued Amount	56,702
AT FAIR VALUE	33,447
Rate	LIBOR
Basis spread on LIBOR	1.53%
Effective Rate	2.98%
Maturity Date of Trust	June 2036
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VIII [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	September 2006
Issued Amount	51,547
AT FAIR VALUE	30,754
Rate	LIBOR
Basis spread on LIBOR	1.63%
Effective Rate	3.12%
Maturity Date of Trust	December 2036
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust IX [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	July 2007
Issued Amount	46,392
AT FAIR VALUE	26,555
Rate	LIBOR
Basis spread on LIBOR	1.40%
Effective Rate	2.86%
Maturity Date of Trust	October 2037
Junior Subordinated Debt, at Fair Value [Member] | Lynnwood Financial Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	March 2003
Issued Amount	9,279
AT FAIR VALUE	7,019
Rate	LIBOR
Basis spread on LIBOR	3.15%
Effective Rate	4.48%
Maturity Date of Trust	March 2033
Junior Subordinated Debt, at Fair Value [Member] | Lynnwood Financial Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	June 2005
Issued Amount	10,310
AT FAIR VALUE	6,407
Rate	LIBOR
Basis spread on LIBOR	1.80%
Effective Rate	3.27%
Maturity Date of Trust	June 2035
Junior Subordinated Debt, at Fair Value [Member] | Klamath First Capital Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	July 2001
Issued Amount	15,464
AT FAIR VALUE	13,049
Rate	LIBOR
Basis spread on LIBOR	3.75%
Effective Rate	4.84%
Maturity Date of Trust	July 2031
Junior Subordinated Debt, at Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	96,037
AT AMORTIZED COST	101,576
Junior Subordinated Debt, at Amortized Cost [Member] | HB Capital Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	March 2000
Issued Amount	5,310
AT AMORTIZED COST	6,161
Debt Instrument, Interest Rate, Stated Percentage	10.875%
Effective Rate	8.46%
Maturity Date of Trust	March 2030
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	February 2001
Issued Amount	5,155
AT AMORTIZED COST	5,780
Debt Instrument, Interest Rate, Stated Percentage	10.20%
Effective Rate	8.42%
Maturity Date of Trust	February 2031
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	September 2003
Issued Amount	10,310
AT AMORTIZED COST	10,310
Rate	LIBOR
Basis spread on LIBOR	2.90%
Effective Rate	3.13%
Maturity Date of Trust	September 2033
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust Ii [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	December 2001
Issued Amount	10,310
AT AMORTIZED COST	11,217
Rate	LIBOR
Basis spread on LIBOR	3.60%
Effective Rate	3.05%
Maturity Date of Trust	December 2031
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust Iii [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	September 2003
Issued Amount	27,836
AT AMORTIZED COST	30,214
Rate	LIBOR
Basis spread on LIBOR	2.95%
Effective Rate	2.51%
Maturity Date of Trust	September 2033
Junior Subordinated Debt, at Amortized Cost [Member] | Cib Capital Trust [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	November 2002
Issued Amount	10,310
AT AMORTIZED COST	11,088
Rate	LIBOR
Basis spread on LIBOR	3.45%
Effective Rate	3.03%
Maturity Date of Trust	November 2032
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	July 2001
Issued Amount	6,186
AT AMORTIZED COST	6,186
Rate	LIBOR
Basis spread on LIBOR	3.58%
Effective Rate	3.82%
Maturity Date of Trust	July 2031
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust Ii [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	December 2001
Issued Amount	10,310
AT AMORTIZED COST	10,310
Rate	LIBOR
Basis spread on LIBOR	3.60%
Effective Rate	3.84%
Maturity Date of Trust	December 2031
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust Iii [Member]
Junior Subordinated Debentures [Line Items]
Issue Date of Trust	September 2003
Issued Amount	10,310
AT AMORTIZED COST	$ 10,310
Rate	LIBOR
Basis spread on LIBOR	2.90%
Effective Rate	3.13%
Maturity Date of Trust	September 2033