Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 475,427
AT FAIR VALUE	250,652	249,294
AT AMORTIZED COST	101,496	101,576
Carrying Value	352,148
Junior Subordinated Debt, at Fair Value [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	379,390
AT FAIR VALUE	250,652
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	20,619
AT FAIR VALUE	15,182
Rate	LIBOR
Basis spread on LIBOR	3.35%
Effective Rate	4.92%
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	30,928
AT FAIR VALUE	22,961
Rate	LIBOR
Basis spread on LIBOR	3.45%
Effective Rate	5.01%
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT FAIR VALUE	7,188
Rate	LIBOR
Basis spread on LIBOR	2.85%
Effective Rate	4.48%
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Statutory Trust V [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT FAIR VALUE	7,166
Rate	LIBOR
Basis spread on LIBOR	2.85%
Effective Rate	4.49%
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Master Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	41,238
AT FAIR VALUE	23,670
Rate	LIBOR
Basis spread on LIBOR	1.35%
Effective Rate	2.81%
Junior Subordinated Debt, at Fair Value [Member] | Umpqua Master Trust IB [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	20,619
AT FAIR VALUE	13,834
Rate	LIBOR
Basis spread on LIBOR	2.75%
Effective Rate	4.50%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	14,433
AT FAIR VALUE	11,165
Rate	LIBOR
Basis spread on LIBOR	3.25%
Effective Rate	4.55%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT FAIR VALUE	7,889
Rate	LIBOR
Basis spread on LIBOR	3.15%
Effective Rate	4.46%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Statutory Trust V [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	20,619
AT FAIR VALUE	15,841
Rate	LIBOR
Basis spread on LIBOR	3.25%
Effective Rate	4.57%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VI [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT FAIR VALUE	7,867
Rate	LIBOR
Basis spread on LIBOR	3.20%
Effective Rate	4.54%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VII [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	56,702
AT FAIR VALUE	33,710
Rate	LIBOR
Basis spread on LIBOR	1.53%
Effective Rate	3.00%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust VIII [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	51,547
AT FAIR VALUE	30,983
Rate	LIBOR
Basis spread on LIBOR	1.63%
Effective Rate	3.15%
Junior Subordinated Debt, at Fair Value [Member] | Sterling Capital Trust IX [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	46,392
AT FAIR VALUE	26,768
Rate	LIBOR
Basis spread on LIBOR	1.40%
Effective Rate	2.88%
Junior Subordinated Debt, at Fair Value [Member] | Lynnwood Financial Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	9,279
AT FAIR VALUE	7,050
Rate	LIBOR
Basis spread on LIBOR	3.15%
Effective Rate	4.50%
Junior Subordinated Debt, at Fair Value [Member] | Lynnwood Financial Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT FAIR VALUE	6,453
Rate	LIBOR
Basis spread on LIBOR	1.80%
Effective Rate	3.30%
Junior Subordinated Debt, at Fair Value [Member] | Klamath First Capital Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	15,464
AT FAIR VALUE	12,925
Rate	LIBOR
Basis spread on LIBOR	3.75%
Effective Rate	4.91%
Junior Subordinated Debt, at Amortized Cost [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	96,037
AT AMORTIZED COST	101,496
Junior Subordinated Debt, at Amortized Cost [Member] | HB Capital Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	5,310
AT AMORTIZED COST	6,147
Debt Instrument, Interest Rate, Stated Percentage	10.875%
Effective Rate	8.44%
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	5,155
AT AMORTIZED COST	5,770
Debt Instrument, Interest Rate, Stated Percentage	10.20%
Effective Rate	8.41%
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT AMORTIZED COST	11,204
Rate	LIBOR
Basis spread on LIBOR	3.60%
Effective Rate	3.04%
Junior Subordinated Debt, at Amortized Cost [Member] | Humboldt Bancorp Statutory Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	27,836
AT AMORTIZED COST	30,182
Rate	LIBOR
Basis spread on LIBOR	2.95%
Effective Rate	2.50%
Junior Subordinated Debt, at Amortized Cost [Member] | CIB Capital Trust [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT AMORTIZED COST	11,077
Rate	LIBOR
Basis spread on LIBOR	3.45%
Effective Rate	3.03%
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	6,186
AT AMORTIZED COST	6,186
Rate	LIBOR
Basis spread on LIBOR	3.58%
Effective Rate	3.82%
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust II [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT AMORTIZED COST	10,310
Rate	LIBOR
Basis spread on LIBOR	3.60%
Effective Rate	3.83%
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust III [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT AMORTIZED COST	10,310
Rate	LIBOR
Basis spread on LIBOR	2.90%
Effective Rate	3.13%
Junior Subordinated Debt, at Amortized Cost [Member] | Western Sierra Statutory Trust IV [Member]
Junior Subordinated Debentures [Line Items]
Issued Amount	10,310
AT AMORTIZED COST	$ 10,310
Rate	LIBOR
Basis spread on LIBOR	2.90%
Effective Rate	3.13%