Regulatory Matters (Tables)

3 Months Ended

Mar. 31, 2012

Regulatory Matters [Abstract]

Actual And Required Capital Ratios

	Actual					Minimum Required for Capital Adequacy Purposes					Required to be Considered Well Capitalized
	Capital Amount		Ratio			Capital Amount		Ratio			Capital Amount		Ratio
March 31, 2012
Total Capital to Risk-Weighted Assets
Cullen/Frost	$	1,844,944		16.10	%	$	916,676		8.00	%	$	1,145,845		10.00	%
Frost Bank		1,657,936		14.48			916,245		8.00			1,145,307		10.00
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost		1,657,763		14.47			458,338		4.00			687,507		6.00
Frost Bank		1,550,755		13.54			458,123		4.00			687,184		6.00
Leverage Ratio
Cullen/Frost		1,657,763		8.68			764,255		4.00			955,319		5.00
Frost Bank		1,550,755		8.12			763,906		4.00			954,882		5.00
December 31, 2011
Total Capital to Risk-Weighted Assets
Cullen/Frost	$	1,835,428		16.24	%	$	903,970		8.00	%	$	1,129,962		10.00	%
Frost Bank		1,641,921		14.54			903,427		8.00			1,129,284		10.00
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost		1,625,281		14.38			451,985		4.00			677,977		6.00
Frost Bank		1,531,774		13.56			451,713		4.00			677,570		6.00
Leverage Ratio
Cullen/Frost		1,625,281		8.66			750,643		4.00			938,304		5.00
Frost Bank		1,531,774		8.17			750,249		4.00			937,811		5.00