Shareholders' Equity Regulatory Capital (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Common Equity Tier 1 (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Common equity Tier 1 Capital to Risk Weighted Assets		4.50%	4.50%
Capital Conservation Buffer, Common equity Tier 1 to Risk Weighted Assets	[1]	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		$ 2,834,532	$ 2,842,193
Common Equity Tier One Risk Based Capital to Risk Weighted Assets		11.21%	12.13%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets		6.00%	6.00%
Capital Conservation Buffer, Tier 1 Capital to Risk Weighted Assets	[1]	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets		8.50%	8.50%
Tier 1 Capital		$ 2,834,532	$ 2,842,193
Tier I Capital to Risk Weighted Assets		11.21%	12.13%
Total Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Total Capital to Risk Weighted Assets		8.00%	8.00%
Capital Conservation Buffer, Total Capital to Risk Weighted Assets	[1]	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets		10.50%	10.50%
Total Capital		$ 3,238,323	$ 3,116,144
Total Capital to Risk Weighted Assets		12.81%	13.30%
Tier I Capital (to Average Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Average Assets		4.00%	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier One Capital to Average Assets		4.00%	4.00%
Tier I Capital to Average Assets		8.72%	9.25%
Phased in Capital Conservation Buffer		0.625%
Fully Phased In Capital Conservation Buffer		2.50%
BOKF, NA [Member]
Common Equity Tier 1 (to Risk Weighted Assets) [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized		6.50%	6.50%
Minimum Capital Requirement, Common equity Tier 1 Capital 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		$ 2,609,450	$ 2,385,323
Common Equity Tier One Risk Based Capital to Risk Weighted Assets		10.65%	10.26%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized		8.00%	8.00%
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets		6.00%	6.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets		6.00%	6.00%
Tier 1 Capital		$ 2,609,450	$ 2,385,323
Tier I Capital to Risk Weighted Assets		10.65%	10.26%
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized		10.00%	10.00%
Minimum Capital Requirement, Total Capital to Risk Weighted Assets		8.00%	8.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets		8.00%	8.00%
Total Capital		$ 2,866,949	$ 2,657,935
Total Capital to Risk Weighted Assets		11.70%	11.43%
Tier I Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized		5.00%	5.00%
Minimum Capital Requirement, Tier 1 Capital to Average Assets		4.00%	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier One Capital to Average Assets		4.00%	4.00%
Tier I Capital to Average Assets		8.11%	7.81%
Mobank [Member]
Common Equity Tier 1 (to Risk Weighted Assets) [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized	[2]	6.50%
Minimum Capital Requirement, Common equity Tier 1 Capital to Risk Weighted Assets	[2]	4.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common equity Tier 1 to Risk Weighted Assets	[2]	4.50%
Common Equity Tier 1 Capital	[2]	$ 54,616
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	[2]	10.03%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized	[2]	8.00%
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	[2]	6.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	[2]	6.00%
Tier 1 Capital	[2]	$ 54,616
Tier I Capital to Risk Weighted Assets	[2]	10.03%
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized	[2]	10.00%
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	[2]	8.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	[2]	8.00%
Total Capital	[2]	$ 54,617
Total Capital to Risk Weighted Assets	[2]	10.03%
Tier I Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized	[2]	5.00%
Minimum Capital Requirement, Tier 1 Capital to Average Assets	[2]	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier One Capital to Average Assets	[2]	4.00%
Tier I Capital to Average Assets	[2]	8.37%

[1] Capital conservation buffer is effective January 1, 2016 and is phased in through 2019. The phased in capital conservation buffer at December 31, 2016 is 0.625%. The fully phased in requirement of 2.50% is included in the table above.

[2] Missouri Bank and Trust Company of Kansas City dba Mobank was acquired by BOK Financial effective December 1, 2016