Capital and Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2021

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Actual and Required Capital Ratios

The following table presents actual and required capital ratios as of December 31, 2021 and December 31, 2020 for Cullen/Frost and Frost Bank under the Basel III Capital Rules. Capital levels required to be considered well capitalized are based upon prompt corrective action regulations, as amended to reflect the changes under the Basel III Capital Rules.

	Actual				Minimum Capital Required - Basel III Fully Phased-In				Required to be Considered Well Capitalized
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
2021
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,371,043	13.13	%	$	1,796,549	7.00	%	$	1,668,224	6.50	%
Frost Bank	3,261,532		12.72		1,795,221		7.00		1,666,991		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,516,495		13.70		2,181,523		8.50		2,053,198		8.00
Frost Bank	3,261,532		12.72		2,179,911		8.50		2,051,681		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,966,244		15.45		2,694,823		10.50		2,566,498		10.00
Frost Bank	3,491,281		13.61		2,692,831		10.50		2,564,601		10.00
Leverage Ratio
Cullen/Frost	3,516,495		7.34		1,917,533		4.00		2,396,917		5.00
Frost Bank	3,261,532		6.80		1,917,679		4.00		2,397,099		5.00
2020
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,058,447	12.86	%	$	1,664,867	7.00	%	$	1,545,948	6.50	%
Frost Bank	3,030,093		12.77		1,661,620		7.00		1,542,933		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,203,899		13.47		2,021,624		8.50		1,902,705		8.00
Frost Bank	3,030,093		12.77		2,017,682		8.50		1,898,995		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,672,912		15.44		2,497,300		10.50		2,378,381		10.00
Frost Bank	3,266,106		13.76		2,492,430		10.50		2,373,743		10.00
Leverage Ratio
Cullen/Frost	3,203,899		8.07		1,589,004		4.00		1,986,255		5.00
Frost Bank	3,030,093		7.63		1,588,200		4.00		1,985,250		5.00