Junior Subordinated Debentures (Junior Subordinated Debentures) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 475,427
Carrying value, at fair value	258,660	$ 255,457
Carrying value, at amortized cost	101,093	$ 101,254
Carrying Value	359,753
Junior Subordinated Debt, at Fair Value
Junior Subordinated Debentures [Line Items]
Issued Amount	379,390
Carrying value, at fair value	258,660
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust II
Junior Subordinated Debentures [Line Items]
Issued Amount	20,619
Carrying value, at fair value	$ 15,593
Variable rate basis	LIBOR
Basis spread on LIBOR	3.35%
Effective rate	5.27%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 30,928
Carrying value, at fair value	$ 23,562
Variable rate basis	LIBOR
Basis spread on LIBOR	3.45%
Effective rate	5.35%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust IV
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 7,411
Variable rate basis	LIBOR
Basis spread on LIBOR	2.85%
Effective rate	4.84%
Junior Subordinated Debt, at Fair Value | Umpqua Statutory Trust V
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 7,374
Variable rate basis	LIBOR
Basis spread on LIBOR	2.85%
Effective rate	4.90%
Junior Subordinated Debt, at Fair Value | Umpqua Master Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 41,238
Carrying value, at fair value	$ 24,658
Variable rate basis	LIBOR
Basis spread on LIBOR	1.35%
Effective rate	3.35%
Junior Subordinated Debt, at Fair Value | Umpqua Master Trust IB
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 20,619
Carrying value, at fair value	$ 14,212
Variable rate basis	LIBOR
Basis spread on LIBOR	2.75%
Effective rate	4.94%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust III
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 14,433
Carrying value, at fair value	$ 11,410
Variable rate basis	LIBOR
Basis spread on LIBOR	3.25%
Effective rate	4.92%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust IV
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 8,066
Variable rate basis	LIBOR
Basis spread on LIBOR	3.15%
Effective rate	4.83%
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	$ 16,169
Variable rate basis	LIBOR
Basis spread on LIBOR	3.25%
Effective rate	4.94%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VI
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at fair value	$ 8,037
Variable rate basis	LIBOR
Basis spread on LIBOR	3.20%
Effective rate	4.94%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VII
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 56,702
Carrying value, at fair value	$ 35,082
Variable rate basis	LIBOR
Basis spread on LIBOR	1.53%
Effective rate	3.52%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust VIII
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 51,547
Carrying value, at fair value	$ 32,182
Variable rate basis	LIBOR
Basis spread on LIBOR	1.63%
Effective rate	3.66%
Junior Subordinated Debt, at Fair Value | Sterling Capital Trust IX
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 46,392
Carrying value, at fair value	$ 27,680
Variable rate basis	LIBOR
Basis spread on LIBOR	1.40%
Effective rate	3.39%
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	$ 7,205
Variable rate basis	LIBOR
Basis spread on LIBOR	3.15%
Effective rate	4.88%
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	$ 6,694
Variable rate basis	LIBOR
Basis spread on LIBOR	1.80%
Effective rate	3.78%
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	$ 13,325
Variable rate basis	LIBOR
Basis spread on LIBOR	3.75%
Effective rate	5.36%
Junior Subordinated Debt, at Amortized Cost
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 96,037
Carrying value, at amortized cost	101,093
Junior Subordinated Debt, at Amortized Cost | HB Capital Trust I
Junior Subordinated Debentures [Line Items]
Issued Amount	5,310
Carrying value, at amortized cost	$ 6,078
Stated interest rate	10.875%
Effective rate	8.58%
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	$ 5,722
Stated interest rate	10.20%
Effective rate	8.51%
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	$ 11,137
Variable rate basis	LIBOR
Basis spread on LIBOR	3.60%
Effective rate	3.45%
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	$ 30,018
Variable rate basis	LIBOR
Basis spread on LIBOR	2.95%
Effective rate	2.91%
Junior Subordinated Debt, at Amortized Cost | CIB Capital Trust
Junior Subordinated Debentures [Line Items]
Issued Amount	$ 10,310
Carrying value, at amortized cost	$ 11,022
Variable rate basis	LIBOR
Basis spread on LIBOR	3.45%
Effective rate	3.41%
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	4.22%
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	4.25%
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	3.53%
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	3.53%