Regulatory Capital (Summary of Company's Capital Amounts And Ratios) (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Consolidated
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 4,770,335	$ 3,651,382
Capital to Risk Weighted Assets	0.1186	0.1371
Capital Required for Capital Adequacy	$ 3,218,301	$ 2,130,565
Capital Required for Capital Adequacy to Risk Weighted Assets	0.0800	0.0800
Capital Required to be Well Capitalized	$ 4,022,876	$ 2,663,207
Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000	0.1000
Tier One Risk Based Capital	$ 3,876,985	$ 2,934,708
Tier One Risk Based Capital to Risk Weighted Assets	0.0964	0.1102
Tier One Risk Based Capital Required for Capital Adequacy	$ 2,413,726	$ 1,597,924
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0600	0.0600
Tier One Risk Based Capital Required to be Well Capitalized	$ 3,218,301	$ 2,130,565
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0800	0.0800
Common Equity Tier One Capital	$ 3,876,985	$ 2,934,708
Common Equity Tier One Capital Ratio	0.0964	0.1102
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,810,294	$ 1,198,443
Tier One Common Equity Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 2,614,869	$ 1,731,084
Tier One Common Equity Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier One Leverage Capital	$ 3,876,985	$ 2,934,708
Tier One Leverage Capital to Average Assets	0.0760	0.0914
Tier One Leverage Capital Required for Capital Adequacy	$ 2,040,344	$ 1,283,669
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	0.0400	0.0400
Tier One Leverage Capital Required to be Well Capitalized	$ 2,550,431	$ 1,604,586
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.0500	0.0500
Umpqua Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 4,653,920	$ 3,440,574
Capital to Risk Weighted Assets	0.1157	0.1292
Capital Required for Capital Adequacy	$ 3,217,821	$ 2,130,240
Capital Required for Capital Adequacy to Risk Weighted Assets	0.0800	0.0800
Capital Required to be Well Capitalized	$ 4,022,276	$ 2,662,799
Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000	0.1000
Tier One Risk Based Capital	$ 4,231,569	$ 3,174,899
Tier One Risk Based Capital to Risk Weighted Assets	0.1052	0.1192
Tier One Risk Based Capital Required for Capital Adequacy	$ 2,413,366	$ 1,597,680
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0600	0.0600
Tier One Risk Based Capital Required to be Well Capitalized	$ 3,217,821	$ 2,130,240
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0800	0.0800
Common Equity Tier One Capital	$ 4,231,569	$ 3,174,899
Common Equity Tier One Capital Ratio	0.1052	0.1192
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,810,024	$ 1,198,260
Tier One Common Equity Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 2,614,479	$ 1,730,820
Tier One Common Equity Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier One Leverage Capital	$ 4,231,569	$ 3,174,899
Tier One Leverage Capital to Average Assets	0.0830	0.0989
Tier One Leverage Capital Required for Capital Adequacy	$ 2,040,489	$ 1,283,610
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	0.0400	0.0400
Tier One Leverage Capital Required to be Well Capitalized	$ 2,550,611	$ 1,604,513
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.0500	0.0500