Available for sale securities actual defaults.

Name:	fnb_AvailableForSaleSecuritiesActualDefaults
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities actual deferrals.

+ Details

Name:	fnb_AvailableForSaleSecuritiesActualDeferrals
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities class.

+ Details

Name:	fnb_AvailableForSaleSecuritiesClass
Namespace Prefix:	fnb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities current par value.

+ Details

Name:	fnb_AvailableForSaleSecuritiesCurrentParValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Available for sale securities expected defaults.

+ Details

Name:	fnb_AvailableForSaleSecuritiesExpectedDefaults
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities lowest credit ratings.

+ Details

Name:	fnb_AvailableForSaleSecuritiesLowestCreditRatings
Namespace Prefix:	fnb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities number of issuers currently performing.

+ Details

Name:	fnb_AvailableForSaleSecuritiesNumberOfIssuersCurrentlyPerforming
Namespace Prefix:	fnb
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Available for sale securities projected recovery rates on current deferrals.

+ Details

Name:	fnb_AvailableForSaleSecuritiesProjectedRecoveryRatesOnCurrentDeferrals
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities actual defaults.

+ Details

Name:	fnb_HeldToMaturitySecuritiesActualDefaults
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities actual deferrals.

+ Details

Name:	fnb_HeldToMaturitySecuritiesActualDeferrals
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities class.

+ Details

Name:	fnb_HeldToMaturitySecuritiesClass
Namespace Prefix:	fnb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Held To Maturity Securities Current Par Value

+ Details

Name:	fnb_HeldToMaturitySecuritiesCurrentParValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Held to maturity securities expected defaults.

+ Details

Name:	fnb_HeldToMaturitySecuritiesExpectedDefaults
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities lowest credit ratings.

+ Details

Name:	fnb_HeldToMaturitySecuritiesLowestCreditRatings
Namespace Prefix:	fnb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities number of issuers currently performing.

+ Details

Name:	fnb_HeldToMaturitySecuritiesNumberOfIssuersCurrentlyPerforming
Namespace Prefix:	fnb
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Held to maturity securities projected recovery rates on current deferrals.

+ Details

Name:	fnb_HeldToMaturitySecuritiesProjectedRecoveryRatesOnCurrentDeferrals
Namespace Prefix:	fnb
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Single issuer trust preferred securities amortized cost.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesAmortizedCost
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Single issuer trust preferred securities current par value.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesCurrentParValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Single issuer trust preferred securities fair value.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesFairValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Single issuer trust preferred securities lowest credit ratings.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesLowestCreditRatings
Namespace Prefix:	fnb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Single issuer trust preferred securities number of issuers currently performing.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesNumberOfIssuersCurrentlyPerforming
Namespace Prefix:	fnb
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Single issuer trust preferred securities unrealized loss.

+ Details

Name:	fnb_SingleIssuerTrustPreferredSecuritiesUnrealizedLoss
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Trust preferred securities amortized cost.

+ Details

Name:	fnb_TrustPreferredSecuritiesAmortizedCost
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Trust Preferred Securities Current Par Value

+ Details

Name:	fnb_TrustPreferredSecuritiesCurrentParValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Trust preferred securities fair value.

+ Details

Name:	fnb_TrustPreferredSecuritiesFairValue
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Trust preferred securities number of issuers currently Performing.

+ Details

Name:	fnb_TrustPreferredSecuritiesNumberOfIssuersCurrentlyPerforming
Namespace Prefix:	fnb
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Trust preferred securities unrealized loss.

+ Details

Name:	fnb_TrustPreferredSecuritiesUnrealizedLoss
Namespace Prefix:	fnb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 16

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 22

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph b

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 14

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 7
-Footnote 2

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. Such gross unrealized losses are the excess of the carrying value of the Available-for-sale Securities over their fair value as of the reporting date. Such gross unrealized losses are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 4, 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 17

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 7, 8, 9, 10, 11

+ Details

Name:	us-gaap_HeldToMaturitySecurities
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 137

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesUnrecognizedHoldingLosses
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration