Shareholders' Equity Regulatory Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Common Equity Tier 1 Capital [Abstract]
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	7.00%	7.00%
Common Equity Tier 1 Capital	$ 4,230,626	$ 3,881,912
Common Equity Tier 1 Capital to Risk Weighted Assets	0.1224	0.1195
Tier I Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	0.0600	0.0600
Capital Conservation Buffer, Tier 1 Capital to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	8.50%	8.50%
Tier 1 Capital	$ 4,235,265	$ 3,881,912
Tier 1 Capital to Risk Weighted Assets	0.1225	0.1195
Total Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	0.0800	0.0800
Capital Conservation Buffer, Total Capital to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	10.50%	10.50%
Total Capital	$ 4,594,787	$ 4,489,110
Total Capital to Risk Weighted Assets	0.1329	0.1382
Tier 1 Capital (to Average Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Average Assets	0.0400	0.0400
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets	4.00%	4.00%
Tier 1 Leverage Capital	$ 4,235,265	$ 3,881,912
Tier 1 Capital to Average Assets	0.0855	0.0828
Subsidiaries [Member] | BOKF, NA [Member]
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized	6.50%	6.50%
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier 1 Capital	$ 3,869,454	$ 3,756,950
Common Equity Tier 1 Capital to Risk Weighted Assets	0.1127	0.1166
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized	0.0800	0.0800
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	0.0600	0.0600
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	6.00%	6.00%
Tier 1 Capital	$ 3,871,457	$ 3,756,950
Tier 1 Capital to Risk Weighted Assets	0.1128	0.1166
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized	0.1000	0.1000
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	0.0800	0.0800
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	8.00%	8.00%
Total Capital	$ 4,164,940	$ 4,153,347
Total Capital to Risk Weighted Assets	0.1213	0.1289
Tier 1 Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized	0.0500	0.0500
Minimum Capital Requirement, Tier 1 Capital to Average Assets	0.0400	0.0400
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets	4.00%	4.00%
Tier 1 Leverage Capital	$ 3,871,457	$ 3,756,950
Tier 1 Capital to Average Assets	0.0784	0.0804