Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 475,427
Carrying value, at fair value	263,605	$ 262,209
Carrying value, at amortized cost	100,851	$ 100,931
Carrying Value	364,456
Junior Subordinated Debt, at Fair Value
Junior Subordinated Debentures [Line Items]
Issued Amount	379,390
Carrying value, at fair value	263,605
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust II
Junior Subordinated Debentures [Line Items]
Issued Amount	20,619
Carrying value, at fair value	$ 15,842
Variable rate basis	LIBOR
Basis spread on LIBOR	3.35%
Effective rate	5.71%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 30,928
Carrying value, at fair value	$ 23,920
Variable rate basis	LIBOR
Basis spread on LIBOR	3.45%
Effective rate	5.80%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust IV
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 7,545
Variable rate basis	LIBOR
Basis spread on LIBOR	2.85%
Effective rate	5.29%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust V
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 7,503
Variable rate basis	LIBOR
Basis spread on LIBOR	2.85%
Effective rate	5.49%
Junior Subordinated Debt, at Fair Value | Umpqua Master Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 41,238
Carrying value, at fair value	$ 25,257
Variable rate basis	LIBOR
Basis spread on LIBOR	1.35%
Effective rate	4.05%
Junior Subordinated Debt, at Fair Value | Umpqua Master Trust IB
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 20,619
Carrying value, at fair value	$ 14,444
Variable rate basis	LIBOR
Basis spread on LIBOR	2.75%
Effective rate	5.54%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 14,433
Carrying value, at fair value	$ 11,559
Variable rate basis	LIBOR
Basis spread on LIBOR	3.25%
Effective rate	5.35%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust IV
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 8,171
Variable rate basis	LIBOR
Basis spread on LIBOR	3.15%
Effective rate	5.29%
Junior Subordinated Debt, at Fair Value | Sterling Capital Statutory Trust V
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 20,619
Carrying value, at fair value	$ 16,371
Variable rate basis	LIBOR
Basis spread on LIBOR	3.25%
Effective rate	5.55%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VI
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 8,141
Variable rate basis	LIBOR
Basis spread on LIBOR	3.20%
Effective rate	5.49%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VII
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 56,702
Carrying value, at fair value	$ 35,912
Variable rate basis	LIBOR
Basis spread on LIBOR	1.53%
Effective rate	4.19%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VIII
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 51,547
Carrying value, at fair value	$ 32,908
Variable rate basis	LIBOR
Basis spread on LIBOR	1.63%
Effective rate	4.33%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust IX
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 46,392
Carrying value, at fair value	$ 28,612
Variable rate basis	LIBOR
Basis spread on LIBOR	1.40%
Effective rate	3.89%
Junior Subordinated Debt, at Fair Value | Lynnwood Financial Statutory Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 9,279
Carrying value, at fair value	$ 7,300
Variable rate basis	LIBOR
Basis spread on LIBOR	3.15%
Effective rate	5.47%
Junior Subordinated Debt, at Fair Value | Lynnwood Financial Statutory Trust II
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 6,841
Variable rate basis	LIBOR
Basis spread on LIBOR	1.80%
Effective rate	4.42%
Junior Subordinated Debt, at Fair Value | Klamath First Capital Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 15,464
Carrying value, at fair value	$ 13,279
Variable rate basis	LIBOR
Basis spread on LIBOR	3.75%
Effective rate	5.95%
Junior Subordinated Debt, at Amortized Cost
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 96,037
Carrying value, at amortized cost	100,851
Junior Subordinated Debt, at Amortized Cost | HB Capital Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	5,310
Carrying value, at amortized cost	$ 6,036
Stated interest rate	10.875%
Effective rate	8.64%
Junior Subordinated Debt, at Amortized Cost | Humboldt Bancorp Statutory Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 5,155
Carrying value, at amortized cost	$ 5,693
Stated interest rate	10.20%
Effective rate	8.55%
Junior Subordinated Debt, at Amortized Cost | Humboldt Bancorp Statutory Trust II
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 11,096
Variable rate basis	LIBOR
Basis spread on LIBOR	3.60%
Effective rate	3.93%
Junior Subordinated Debt, at Amortized Cost | Humboldt Bancorp Statutory Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 27,836
Carrying value, at amortized cost	$ 29,921
Variable rate basis	LIBOR
Basis spread on LIBOR	2.95%
Effective rate	3.38%
Junior Subordinated Debt, at Amortized Cost | CIB Capital Trust
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 10,989
Variable rate basis	LIBOR
Basis spread on LIBOR	3.45%
Effective rate	3.81%
Junior Subordinated Debt, at Amortized Cost | Western Sierra Statutory Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 6,186
Carrying value, at amortized cost	$ 6,186
Variable rate basis	LIBOR
Basis spread on LIBOR	3.58%
Effective rate	4.62%
Junior Subordinated Debt, at Amortized Cost | Western Sierra Statutory Trust II
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 10,310
Variable rate basis	LIBOR
Basis spread on LIBOR	3.60%
Effective rate	4.75%
Junior Subordinated Debt, at Amortized Cost | Western Sierra Statutory Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 10,310
Variable rate basis	LIBOR
Basis spread on LIBOR	2.90%
Effective rate	3.92%
Junior Subordinated Debt, at Amortized Cost | Western Sierra Statutory Trust IV
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 10,310
Variable rate basis	LIBOR
Basis spread on LIBOR	2.90%
Effective rate	3.92%