Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015 item	Mar. 31, 2014	Dec. 31, 2014
Segment Information
Number of business segments	3us-gaap_NumberOfReportableSegments
Segment reporting
Net interest income	$ 27,439us-gaap_InterestIncomeExpenseNet	$ 25,667us-gaap_InterestIncomeExpenseNet
Provision for loan losses	130us-gaap_ProvisionForLoanAndLeaseLosses	1,926us-gaap_ProvisionForLoanAndLeaseLosses
Non-interest income	17,604us-gaap_NoninterestIncome	8,668us-gaap_NoninterestIncome
Non-interest expense	24,143us-gaap_NoninterestExpense	25,790us-gaap_NoninterestExpense
Provision for income taxes	7,038us-gaap_IncomeTaxExpenseBenefit	2,329us-gaap_IncomeTaxExpenseBenefit
Net income	13,732	4,290
Total Assets	3,446,770us-gaap_Assets	3,143,337us-gaap_Assets	3,399,134us-gaap_Assets
Average Assets	3,381,660cfnl_AverageAssets	3,021,873cfnl_AverageAssets
Operating segment \| Commercial Banking
Segment reporting
Net interest income	27,105	25,193
Provision for loan losses	130	1,926
Non-interest income	1,278	932
Non-interest expense	15,146	15,792
Provision for income taxes	4,215	2,895
Net income	8,892	5,512
Total Assets	3,371,660	3,095,847
Average Assets	3,322,472	2,943,545
Operating segment \| Mortgage Banking
Segment reporting
Net interest income	511	638
Non-interest income	16,216	7,391
Non-interest expense	7,319	8,293
Provision for income taxes	3,434	(97)
Net income	5,974	(167)
Total Assets	358,024	321,958
Average Assets	267,313	230,424
Operating segment \| Wealth Management and Trust Services
Segment reporting
Non-interest income	105	167
Non-interest expense	104	112
Provision for income taxes		19
Net income	1	36
Total Assets	2,391	2,301
Average Assets	2,409	2,300
Other.
Segment reporting
Net interest income	(177)	(164)
Non-interest income	5	178
Non-interest expense	1,574	1,593
Provision for income taxes	(611)	(488)
Net income	(1,135)	(1,091)
Total Assets	415,545	387,898
Average Assets	417,547	379,810
Intersegment Elimination
Segment reporting
Total Assets	(700,850)	(664,667)
Average Assets	$ (628,081)	$ (534,206)

Average carrying amount of assets during the reporting period.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The net amount of operating interest income (expense).

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Total aggregate amount of all noninterest expense.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of expense related to estimated loss from loan and lease transactions.

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