Convertible Debt Instrument, Conversion Ratio, Principal Amount, Basis

No definition available.

Name:	nhi_ConvertibleDebtInstrumentConversionRatioPrincipalAmountBasis
Namespace Prefix:	nhi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of current revolving borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

No definition available.

+ Details

Name:	nhi_CreditFacilityCurrentRevolvingBorrowingCapacity
Namespace Prefix:	nhi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents the contractual minimum for a variable rate basis such as LIBOR for a debt instrument.

+ References

No definition available.

+ Details

Name:	nhi_DebtInstrumentVariableRateBasisMinimum
Namespace Prefix:	nhi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the net book value of real estate pledged toward mortgage.

+ References

No definition available.

+ Details

Name:	nhi_NetBookValueofRealEstatePledgedTowardMortgage
Namespace Prefix:	nhi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This concept represents the outstanding balance of term loans.

+ References

No definition available.

+ Details

Name:	nhi_TermLoansOutstandingBalance
Namespace Prefix:	nhi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in additional paid in capital (APIC) resulting from recognition of deferred taxes for convertible debt with a beneficial conversion feature.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 55
-Paragraph 51
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-Subparagraph (SX 210.3-04)
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of all asset derivatives designated as cash flow hedging instruments.

+ References

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-Publisher FASB
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-Paragraph 4B
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+ Details

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

- Definition

Fair value of all liability derivatives designated as cash flow hedging instruments.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The price per share of the conversion feature embedded in the debt instrument.

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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Balance Type:	na
Period Type:	duration

- Definition

The number of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1930-109256

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Balance Type:	na
Period Type:	duration

- 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.

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-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

+ Details

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Data Type:	num:percentItemType
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- Definition

The loss recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the contractual principal due at the origination of the mortgage loan (face amount).

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The stated interest rate on the mortgage loan receivable or the weighted average interest rate on a group of loans.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates the number of mortgages under each classification.

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- Definition

Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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- Definition

The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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- Definition

Dividend or interest rate associated with the financial or equity instrument issued as noncash or part noncash consideration for a business or asset acquired. Noncash are transactions that affect recognized assets or liabilities but that do not result in cash receipts or cash payments. Part noncash refers to that portion of the transaction not resulting in cash receipts or cash payments.

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- Definition

The total amount of [all] liabilities that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

+ References

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- Definition

The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

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- Definition

Amount of lien or mortgage outstanding on real estate investment properties for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule III)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

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Debt (Narrative) (Details)	3 Months Ended		12 Months Ended
Debt (Narrative) (Details)	Mar. 31, 2018 USD ($) properties shares	Mar. 31, 2017 USD ($) shares	Dec. 31, 2017 USD ($) properties shares number_of_loans $ / shares	Mar. 31, 2014 USD ($)
Loss on Cash Flow Hedge Ineffectiveness	$ (353,000)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	235,000
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	775,000
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	290,000	$ 824,000
Line of Credit Facility, Maximum Borrowing Capacity	800,000,000
Debt Instrument, Convertible, Conversion Ratio			14.28
Debt Instrument, Convertible, Conversion Price \| $ / shares			$ 70.01
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 192,238,000			$ 7,762,000
Debt Instrument, Convertible, Number of Equity Instruments \| shares			1,714,100
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities \| shares	0	98,048
Convertible Debt	$ 118,041,000		$ 144,938,000
Debt Instrument, Interest Rate, Effective Percentage			3.90%
Unamortized Debt Issuance Expense			$ 10,453,000
Gain (Loss) on Extinguishment of Debt	$ (738,000)	$ 0
Debt Instrument, Variable Rate Basis, Minimum	0.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	2000.00%
Credit Facility, Current Revolving Borrowing Capacity	$ 550,000,000
Number of Real Estate Properties \| properties			210
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value			$ (588,000)
Bank Term Loans [Member]
Term Loans, Outstanding Balance	$ 250,000,000
Debt Instrument, Basis Spread on Variable Rate	13000.00%
Debt Instrument, Name, Convertible Senior Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage			3.25%
Debt Instrument, Face Amount			$ 120,000,000
Convertible Debt Instrument, Conversion Ratio, Principal Amount, Basis	$ 1,000
Payments of Debt Issuance Costs			6,063,000
Unamortized Debt Issuance Expense			1,300,000
Payment for Debt Extinguishment or Debt Prepayment Cost	$ 144,938,000		26,821,000
Gain (Loss) on Extinguishment of Debt			738,000
Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature			2,427,000
At Inception [Member]
Proceeds from convertible senior notes			$ 200,000,000
Debt Instrument, Convertible, Conversion Ratio			13.93
Debt Instrument, Convertible, Conversion Price \| $ / shares			$ 71.81
Debt Instrument, Convertible, Number of Equity Instruments \| shares			2,785,200
Debt Instrument, Name, Revolving Credit Facility [Member]
Debt Instrument, Basis Spread on Variable Rate	11500.00%
Unused balance of the unsecured revolving credit facility	$ 288,000,000
FNMA Berkadia Note [Member]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate			4.60%
Debt Instrument, Name, Fannie Mae Term Loans [Member]
Debt Instrument, Term			10 years
Mortgage Loans on Real Estate, Face Amount of Mortgages			$ 78,084,000
Debt Instrument, Interest Rate, Stated Percentage			3.79%
Number of Real Estate Properties			13
Net Book Value of Real Estate Pledged Toward Mortgage			$ 141,189,000
Debt Instrument, Name, HUD Mortgages [Member]
Number of Real Estate Properties \| properties			10
Net Book Value of Real Estate Pledged Toward Mortgage			$ 52,156,000
Debt Instrument, Name, HUD Mortgages [Member] \| Minimum [Member]
Mortgage Loans on Real Estate, Interest Rate			4.30%
Debt Instrument, Name, HUD Mortgages [Member] \| Maximum [Member]
Mortgage Loans on Real Estate, Interest Rate			4.40%
Debt Instrument, HUD Mortgages, 2049 Maturity [Member]
Mortgage Loans on Real Estate, Number of Loans \| number_of_loans			9
Debt Instrument, HUD Mortgages, 2047 Maturity [Member]
Mortgage Loans on Real Estate, Number of Loans \| number_of_loans			1
Allocated to Debt [Member] \| Debt Instrument, Name, Convertible Senior Notes [Member]
Payments of Debt Issuance Costs			$ 5,788,000
Allocated to Equity [Member] \| Debt Instrument, Name, Convertible Senior Notes [Member]
Payments of Debt Issuance Costs			$ 275,000
Bickford Senior Living [Member]
Number of Real Estate Properties \| properties	47
Middletown, OH [Member] \| Bickford Senior Living [Member]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Rate			2.90%
Fair Value, Inputs, Level 2 [Member]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	$ 1,332,000		$ 159,000
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	$ 0		(747,000)
Real Estate Acquisition [Member] \| Discovery Senior Living [Member]
Noncash or Part Noncash Acquisition, Debt Assumed			18,311,000
Independent Living Facility [Member] \| Tulsa, OK [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances			$ 18,201,000