FAIR VALUE MEASUREMENTS - Narrative (Details) (USD $)
|
3 Months Ended | 12 Months Ended |
---|---|---|
Mar. 31, 2015
|
Dec. 31, 2014
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Unrealized losses forecasted to be included in earnings transferred from AOCI in the next twelve months | $ 1,300,000us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet | |
Reported Value Measurement [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Fixed rate mortgages, fair value |
158,000,000us-gaap_LoansPayableFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember |
153,400,000us-gaap_LoansPayableFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember |
Level 2 [Member] | Recurring [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Fixed rate mortgages, fair value |
165,700,000us-gaap_LoansPayableFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
158,300,000us-gaap_LoansPayableFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
Weighted average market interest rate |
3.35%nsa_FairValueAssumptionsWeightedAverageMarketInterestRate / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
3.59%nsa_FairValueAssumptionsWeightedAverageMarketInterestRate / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
Weighted average contractual interest rate |
5.06%nsa_FairValueAssumptionsWeightedAverageContractualInterestRate / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
5.11%nsa_FairValueAssumptionsWeightedAverageContractualInterestRate / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Notional amount |
125,000,000.0invest_DerivativeNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_DesignatedAsHedgingInstrumentMember |
125,000,000.0invest_DerivativeNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_DesignatedAsHedgingInstrumentMember |
Weighted average remaining term | 3 years | |
Weighted average fixed rate |
1.42%us-gaap_DerivativeAverageFixedInterestRate / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_DesignatedAsHedgingInstrumentMember |
|
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Notional amount |
$ 7,600,000invest_DerivativeNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_NondesignatedMember |
$ 7,600,000.0invest_DerivativeNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_NondesignatedMember |
Weighted average remaining term | 6 years 10 months 18 days | |
Weighted average fixed rate |
2.28%us-gaap_DerivativeAverageFixedInterestRate / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_HedgingDesignationAxis = us-gaap_NondesignatedMember |
X | ||||||||||
- Definition
Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Definition
Fair Value Assumptions, Weighted Average Contractual Interest Rate No definition available.
|
X | ||||||||||
- Definition
Fair Value Assumptions, Weighted Average Market Interest Rate No definition available.
|
X | ||||||||||
- Definition
Average fixed interest rate related to the group of interest rate derivatives. No definition available.
|
X | ||||||||||
- Definition
Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available.
|
X | ||||||||||
- Details
|
X | ||||||||||
- Definition
The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Definition
Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates. No definition available.
|
X | ||||||||||
- Details
|
X | ||||||||||
- Details
|
X | ||||||||||
- Details
|
X | ||||||||||
- Details
|