Disclosures Regarding Fair Value - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets
Impaired loans in gross loans	$ 1,073
Foreclosed real estate and repossessed personal property	8,528
Long-lived assets held for sale	685
Total assets measured at fair value on a nonrecurring basis	266,148	264,872
Level 1 [Member]
Assets
Total assets measured at fair value on a nonrecurring basis	43,180	58,740
Level 2 [Member]
Assets
Total assets measured at fair value on a nonrecurring basis	222,968	206,132
Level 3 [Member]
Assets
Total assets measured at fair value on a nonrecurring basis
Nonrecurring [Member]
Assets
Mortgage loans held for sale	7,056	6,114
Other loans held for sale	800	800
Impaired loans in gross loans	7,122	6,474
Foreclosed real estate and repossessed personal property	9,283	9,980
Long-lived assets held for sale	685	685
Total assets measured at fair value on a nonrecurring basis	24,946	24,053
Nonrecurring [Member] \| Level 1 [Member]
Assets
Mortgage loans held for sale
Other loans held for sale		800
Impaired loans in gross loans
Foreclosed real estate and repossessed personal property	105
Long-lived assets held for sale
Total assets measured at fair value on a nonrecurring basis	105	800
Nonrecurring [Member] \| Level 2 [Member]
Assets
Mortgage loans held for sale	7,056	6,114
Other loans held for sale	800
Impaired loans in gross loans	6,049	6,285
Foreclosed real estate and repossessed personal property	650	817
Long-lived assets held for sale
Total assets measured at fair value on a nonrecurring basis	14,555	13,216
Nonrecurring [Member] \| Level 3 [Member]
Assets
Mortgage loans held for sale
Other loans held for sale
Impaired loans in gross loans	1,073	189
Foreclosed real estate and repossessed personal property	8,528	9,163
Long-lived assets held for sale	685	685
Total assets measured at fair value on a nonrecurring basis	$ 10,286	$ 10,037

Foreclosed and repossessed assets fair value.

No definition available.

Name:	plmt_ForeclosedAndRepossessedAssetsFairValue
Namespace Prefix:	plmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Impaired loans fair value disclosure.

+ References

No definition available.

+ Details

Name:	plmt_ImpairedLoansFairValueDisclosure
Namespace Prefix:	plmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Definition

Long-lived assets that are held for sale apart from normal operations and anticipated to be sold in less than one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 33

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loans held-for-sale as presented on the statement of financial position which may include mortgage loans held-for-sale, finance receivables held-for-sale, or any other loans classified as held-for-sale which are due the Company as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansHeldForSaleFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents mortgage loans held-for-sale as presented on the statement of financial position which are due the Company as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_MortgagesHeldForSaleFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant