XML 134 R117.htm IDEA: XBRL DOCUMENT
v3.20.4

Other Non-Interest Income and Expense (Narrative) (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Other Income and Expenses [Abstract] |  |  |
Minimum percentage of the aggregate total net interest income and total non interest income required for amounts to be stated separately | 1.00% | 1.00% | 1.00%
Payment for services provided by related party | $ 551 | $ 567 | $ 568

X
- Definition Minimum Percentage Of Aggregate Net Interest Income And Non Interest Income Required For Amounts To Be Stated Separately + References No definition available. + Details
Name: | cfr_MinimumPercentageOfAggregateNetInterestIncomeAndNonInterestIncomeRequiredForAmountsToBeStatedSeparately
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Costs of sales and operating expenses for the period incurred from transactions with related parties. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_CostsAndExpensesRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_OtherIncomeAndExpensesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration