Regulatory Capital (Summary of Company's Capital Amounts And Ratios) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Consolidated [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 2,391,267	$ 1,279,586
Capital to Risk Weighted Assets	15.20%	14.66%
Capital Required for Capital Adequacy	1,258,198	698,273
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	1,572,747	872,842
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Risk Based Capital	2,271,563	1,183,061
Tier One Risk Based Capital to Risk Weighted Assets	14.44%	13.56%
Tier One Risk Based Capital Required for Capital Adequacy	629,099	348,986
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	943,648	523,478
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Tier One Leverage Capital	2,271,563	1,183,061
Tier One Leverage Capital to Average Assets	10.99%	10.90%
Tier One Leverage Capital Required for Capital Adequacy	827,128	434,151
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	1,033,910	542,689
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Umpqua Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	2,181,776	1,177,782
Capital to Risk Weighted Assets	13.90%	13.51%
Capital Required for Capital Adequacy	1,255,819	697,428
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	1,569,774	871,785
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Risk Based Capital	2,062,151	1,081,282
Tier One Risk Based Capital to Risk Weighted Assets	13.14%	12.40%
Tier One Risk Based Capital Required for Capital Adequacy	627,910	348,801
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	941,864	523,201
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Tier One Leverage Capital	2,062,151	1,081,282
Tier One Leverage Capital to Average Assets	9.96%	9.97%
Tier One Leverage Capital Required for Capital Adequacy	828,061	433,814
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 1,035,076	$ 542,268
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%