Capital and Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2016

Regulatory Capital Requirements [Abstract]

Actual and Required Capital Ratios

	Actual				Minimum Capital Required - Basel III Phase-In Schedule				Minimum Capital Required - Basel III Fully Phased-In				Required to be Considered Well Capitalized
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
2016
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	2,239,186	12.52	%	$	916,360	5.125	%	$	1,251,425	7.00	%	$	1,162,213	6.50	%
Frost Bank	2,296,480		12.88		913,460		5.125		1,247,463		7.00		1,158,535		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	2,383,672		13.33		1,184,563		6.625		1,519,587		8.50		1,430,416		8.00
Frost Bank	2,296,480		12.88		1,180,814		6.625		1,514,776		8.50		1,425,889		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	2,669,717		14.93		1,542,168		8.625		1,877,137		10.50		1,788,020		10.00
Frost Bank	2,449,525		13.74		1,537,286		8.625		1,871,194		10.50		1,782,361		10.00
Leverage Ratio
Cullen/Frost	2,383,672		8.14		1,171,682		4.00		1,171,573		4.00		1,464,602		5.00
Frost Bank	2,296,480		7.85		1,170,249		4.00		1,170,141		4.00		1,462,812		5.00
2015
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	1,986,200	11.37	%	$	786,344	4.50	%	$	1,222,837	7.00	%	$	1,135,830	6.50	%
Frost Bank	2,131,360		12.24		783,727		4.50		1,218,766		7.00		1,132,049		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	2,163,936		12.38		1,048,458		6.00		1,484,874		8.50		1,397,944		8.00
Frost Bank	2,131,360		12.24		1,044,969		6.00		1,479,930		8.50		1,393,292		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	2,419,545		13.85		1,397,944		8.00		1,834,256		10.50		1,747,430		10.00
Frost Bank	2,267,219		13.02		1,393,292		8.00		1,828,149		10.50		1,741,615		10.00
Leverage Ratio
Cullen/Frost	2,163,936		7.79		1,111,325		4.00		1,111,117		4.00		1,389,156		5.00
Frost Bank	2,131,360		7.68		1,110,143		4.00		1,109,935		4.00		1,387,679		5.00