Derivative - Schedule of Interest Rate Swap Agreements (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount	$ 6,710,773	$ 2,696,100
1.5120% Interest Rate Swap
Derivative [Line Items]
Effective Date	Jun. 30, 2015
Maturity Date	Dec. 31, 2019
Notional Amount	$ 300,000
Fixed Rate	1.512%
Variable Rate	1 Month LIBOR
1.5995% Interest Rate Swap
Derivative [Line Items]
Effective Date	Mar. 08, 2016
Maturity Date	Feb. 27, 2026
Notional Amount	$ 175,000
Fixed Rate	1.5995%
Variable Rate	1 Month LIBOR
1.5890% Interest Rate Swap
Derivative [Line Items]
Effective Date	Mar. 08, 2016
Maturity Date	Feb. 27, 2026
Notional Amount	$ 175,000
Fixed Rate	1.589%
Variable Rate	1 Month LIBOR

Derivative instrument effective date.

No definition available.

Name:	cade_DerivativeInstrumentEffectiveDate
Namespace Prefix:	cade_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

When the derivative or group of derivatives presented is a swap, the type of interest rate (fixed, variable, stepped, etc.) paid on the swap.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column A
-Footnote 1

+ Details

Name:	invest_DerivativeTypeOfInterestRatePaidOnSwap
Namespace Prefix:	invest_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the derivative contract matures, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeMaturityDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cade_OnePointFiveOneTwoZeroPercentInterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cade_OnePointFiveNineNineFivePercentInterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cade_OnePointFiveEightNineZeroPercentInterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: